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Abstract:

Systems and methods for obtaining and processing data collected using a
multi-site intravascular sensing device are provided. Some embodiments
are directed to locating a structure within a vessel and performing an
examination of the structure once it has been located. In one embodiment,
an elongate member has a plurality of sensors and set of measurements is
obtained using the plurality of sensors, the set of measurements
including at least one measurement from each sensor of the plurality of
sensors. The various sensor measurements are compared and a difference in
a vascular characteristic is determined from the compared measurements.
The location of the structure may be determined based on the adjacent
sensors.

Claims:

1. A method of locating a structure within a vessel, the method
comprising: obtaining a set of measurements from a plurality of sensors
disposed along an elongate member of a sensing instrument positioned
within the vessel, the set of measurements including at least one
measurement from each sensor of the plurality of sensors; comparing
measurements of the set of measurements across sensors of the plurality
of sensors; determining a difference in a vascular characteristic from
the compared measurements, the difference corresponding to the structure
of the vessel; determining sensors in proximity to the structure based on
the determined difference in the vascular characteristic; and determining
a location of the structure within the vessel based on the determined
sensors.

2. The method of claim 1, wherein the sensors include ultrasound
transducers; wherein the set of measurements includes ultrasound echo
data; and wherein the difference corresponds to a difference in
ultrasound echo strength.

3. The method of claim 1, wherein the sensors include optical coherence
tomography transceivers; wherein the set of measurements includes
interferometry measurements; and wherein the difference corresponds to a
tomographic difference.

4. The method of claim 1, wherein the sensors include pressure sensors;
wherein the set of measurements includes pressure data; and wherein the
difference corresponds to a difference in fluid pressure.

5. The method of claim 4, wherein the structure includes a plurality of
stenoses, the method further comprising determining an individual effect
of each stenosis of the plurality of stenoses by, for each stenosis of
the plurality of stenoses: obtaining a proximal pressure measurement at a
location proximal to the stenosis, the proximal location being
substantially between the stenosis and any proximal stenosis of the
plurality of stenoses; obtaining a distal pressure measurement at a
location distal to the stenosis, the distal location being substantially
between the stenosis and any distal stenosis of the plurality of
stenoses; and calculating a pressure ratio between the distal pressure
measurement and the proximal pressure measurement for the stenosis.

6. The method of claim 5 further comprising determining a cumulative
effect of the plurality of stenoses by: obtaining a proximal-most
pressure measurement at a location proximal to all stenoses of the
plurality of stenoses; obtaining a distal-most pressure measurement at a
location distal to all stenoses of the plurality of stenoses; and
calculating another pressure ratio between the distal-most pressure
measurement and the proximal-most pressure measurement for the plurality
of stenoses.

7. The method of claim 1, wherein the elongate member has a detailed
sensing region, the method further comprising: adjusting the location of
the elongate member within the vessel such that the detailed sensing
region is adjacent to the determined location of the structure; and
obtaining a second set of measurements using sensors disposed within the
detailed sensing region.

8. The method of claim 7, wherein the detailed sensing region is defined
by a closer sensor spacing than a sensor spacing of a remaining portion
of the elongate member.

9. The method of claim 7, wherein the detailed sensing region includes a
sensor having a higher sensing resolution than a sensor of a remaining
portion of the elongate member.

10. The method of claim 7, wherein the set of measurements corresponds to
a first modality, wherein the second set of measurements corresponds to a
second modality; and wherein the first modality and the second modality
are different.

11. The method of claim 10, wherein the first modality is one of pressure
and fluid flow, and wherein the second modality is one of intravascular
ultrasound and optical coherence tomography.

12. A method of evaluating a vessel region, the method comprising:
obtaining a first set of measurements using a first subset of a plurality
of sensors of a sensing instrument positioned within the vessel region,
the sensing instrument having a longitudinally elongated sensing portion
including the plurality of sensors, the first set of measurements
corresponding to a first sensing modality; presenting the first set of
measurements at a display device; receiving a user input specifying a
segment of the vessel region following the presenting of the first set of
measurements at the user display; and obtaining a second set of
measurements using a second subset of the plurality of sensors, wherein
the second set of measurements relate to the specified segment of the
vessel region; and wherein the second set of measurements is obtained
without adjusting a position of the sensing portion between the obtaining
of the first set of measurements and the obtaining of the second set of
measurements.

13. The method of claim 12, wherein the specified segment is a first
specified segment, the method further comprising: receiving a second user
input specifying a second segment of the vessel region; and obtaining a
third set of measurements using a third subset of the plurality of
sensors, wherein the third set of measurements relate to the second
specified segment of the vessel region; and wherein the third set of
measurements is obtained without adjusting the position of the sensing
portion between the obtaining of the second set of measurements and the
obtaining of the third set of measurements.

14. The method of claim 12, wherein the presenting of the first set of
measurements highlights at least one of a bifurcation, a stenosis, a
plaque, a vascular dissection, a lesion, and a stent.

15. The method of claim 12, wherein the second set of measurements
corresponds to a second sensing modality different from the first sensing
modality.

16. The method of claim 15, wherein the first sensing modality is a
structural intravascular ultrasound modality.

17. The method of claim 16, wherein the second modality is a flow
modality.

18. The method of claim 16, wherein the second modality is one of a
pressure modality, a flow modality, and an optical coherence tomography
modality.

19. The method of claim 15, wherein the first sensing modality is a
pressure modality.

20. The method of claim 19, wherein the obtaining of the first set of
measurements includes determining a fractional flow reserve ratio.

21. The method of claim 20, wherein the second sensing modality is an
intravascular ultrasound modality.

22. A method of displaying data by simulating an intravascular procedure,
the method comprising: determining portions of the vessel corresponding
to and in proximity to each sensor of a sensing instrument positioned
within the vessel, the sensing instrument having a plurality of sensors;
presenting an indicator of each of the portions of the vessel at a user
display; receiving a user selection of a designated vascular portion, the
designated vascular portion being one of the determined portions of the
vessel; collecting medical data from a sensor corresponding to the
designated vascular portion; and displaying the collected medical data.

23. The method of claim 22, wherein plurality of sensors includes a
plurality of ultrasound transceivers, and wherein the collected medical
data includes intravascular ultrasound echo data.

24. The method of claim 22, wherein the plurality of sensors includes a
plurality of optical coherence tomography transducers, and wherein the
collected data includes interferometry measurements.

25. The method of claim 22, wherein the plurality of sensors includes a
plurality of pressure sensors, and wherein the collected medical data
includes pressure data.

26. The method of claim 25 further comprising determining a fractional
flow reserve ratio for the designated vascular portion, and wherein the
displaying of the collected data displays the fractional flow reserve
ratio.

27. The method of claim 25 further comprising, for each of the portions
of the vessel: determining a distal sensor at a location distal to the
portion; and determining a proximal sensor at a location proximal to the
portion, wherein the determining of the fractional flow reserve ratio
includes determining an individual fractional flow reserve ratio for the
portion using the distal sensor and the proximal sensor.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of U.S.
Provisional Patent Application No. 61/745,491, filed Dec. 21, 2012, which
is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] This present disclosure relates generally to the field of medical
devices, and more particularly, to the collection and processing of
multi-site measurements of vascular health.

BACKGROUND

[0003] Innovations in diagnosing and verifying the level of success of
treatment of disease have migrated from external imaging processes to
internal diagnostic processes. In particular, diagnostic equipment and
processes have been developed for diagnosing vasculature blockages and
other vasculature disease by means of ultra-miniature sensors placed upon
the distal end of a flexible elongate member such as a catheter, or a
guide wire used for catheterization procedures. For example, known
medical sensing techniques include angiography, intravascular ultrasound
(IVUS), forward looking IVUS (FL-IVUS), fractional flow reserve (FFR)
determination, a coronary flow reserve (CFR) determination, optical
coherence tomography (OCT), trans-esophageal echocardiography, and
image-guided therapy. Each of these techniques may be better suited for
different diagnostic situations. To increase the chance of successful
treatment, health care facilities may have a multitude of imaging,
treatment, diagnostic, and sensing modalities on hand in a catheter lab
during a procedure. Recently, processing systems have been designed that
collect medical data from a plurality of different imaging, treatment,
diagnostic, and sensing tools and process the multi-modality medical
data. Such multi-component systems place a wealth of medical information
at the operator's command.

[0004] While existing multi-modality medical systems have proved useful,
they have not necessarily been utilized to their full potential. Some
existing intravascular devices are held back by their limited sensing
areas. This may make it difficult to align the sensors with the vascular
area to be imaged, particular when the area to be imaged cannot be
precisely located using external means. Other surgical devices are
limited by the number of sensing modalities available on a single device.
Thus, imaging systems that incorporate a greater number and greater
diversity of sensors have the potential to pave the way for new
diagnostic and therapeutic practices and to bring improved accuracy to
those practices already in existence.

SUMMARY

[0005] Embodiments of the present disclosure provide systems and methods
for collecting and navigating multi-modality medical data utilizing a
sensing instrument having a plurality of sensors disposed along the
length.

[0006] The systems and methods of the present disclosure allow operators
to locate and analyze vascular abnormalities. A sensing instrument is
guided into the general area of the structure to be examined, and a
series of measurements is taken along the length of instrument. The
location of the structure to be examined can be determined from the
location of the sensors that detect the structure. In many applications,
this allows for rapid discovery of abnormalities that cannot be resolved
using external imaging. In some cases, once the structure is located,
detailed measurements can then be taken by activating additional sensors
adjacent to the structure and without relocating the instrument. By
stepping through the sensors along the length of the instrument, the
instrument may be used to perform a virtual pullback similar to the
physical pullback familiar to users. In other cases, additional sensors
can be moved into position to examine the structure without exchanging
devices. Of course, it is understood that these advantages are merely
exemplary, and no particular advantage is required for any particular
embodiment.

[0007] In some embodiments, a method of locating a structure within a
vessel is provided. The method comprises advancing an elongate member of
a sensing instrument into the vessel. The elongate member has a plurality
of sensors disposed along the elongate member. A set of measurements is
obtained using the plurality of sensors, where the set of measurements
includes at least one measurement from each sensor of the plurality of
sensors. The measurements of the set of measurements are compared across
sensors of the plurality of sensors. A difference in a vascular
characteristic corresponding to the structure of the vessel is determined
from the compared measurements, the difference. Sensors in proximity to
the structure are determined based on the determined difference in the
vascular characteristic, and a location of the structure within the
vessel is determined based on the determined sensors.

[0008] In some embodiments, a method of evaluating a vessel region is
provided. The method comprises introducing a sensing instrument having a
longitudinally elongated sensing portion into the vessel region such that
the sensing portion extends through the vessel region. The sensing
portion has a plurality of sensors disposed therein. A first set of
measurements corresponding to a first sensing modality is obtained using
a first subset of the plurality of sensors and is presented at a display
device. A user input specifying a segment of the vessel region is
received following the presenting of the first set of measurements at the
user display, and a second set of measurements is obtained using a second
subset of the plurality of sensors. The second set of measurements relate
to the specified segment of the vessel region and is obtained without
adjusting a position of the sensing portion between the obtaining of the
first set of measurements and the obtaining of the second set of
measurements.

[0009] In some embodiments, a method of displaying data by simulating an
intravascular procedure is provided. The method comprises advancing a
sensing instrument into a vessel to be visualized. The sensing instrument
has a plurality of sensors disposed therein. Portions of the vessel
corresponding to and in proximity to each sensor of the plurality of
sensors are determined and an indicator of each of the portions of the
vessel is presented at a user display. A user selection of a designated
vascular portion is received, the designated vascular portion being one
of the determined portions of the vessel. Medical data is collected from
a sensor corresponding to the designated vascular portion, and the
collected medical data is displayed.

[0010] Additional aspects, features, and advantages of the present
disclosure will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIGS. 1A, 1B, and 1C are schematic drawings depicting a medical
system including an invasive intravascular system in various applications
according to some embodiments of the present disclosure. In particular,
FIG. 1A is illustrative of the medical system in a catheterization
procedure according to some embodiments of the present disclosure. FIG.
1B is illustrative of the medical system in a cardiac catheterization
procedure according to some embodiments of the present disclosure. FIG.
1C is illustrative of the medical system in a renal catheterization
procedure according to some embodiments of the present disclosure.

[0012] FIG. 2 is a diagrammatic schematic view of a medical sensing system
according to some embodiments of the present disclosure.

[0013] FIG. 3 is a diagrammatic schematic view of a portion of a medical
sensing system according to some embodiments of the present disclosure.

[0014] FIG. 4 is a diagrammatic schematic view of a portion of an optical
sensing system according to some embodiments of the present disclosure.

[0015] FIGS. 5A and 5B are diagrammatic schematic views of a medical
sensing device used in a catheterization procedure according to some
embodiments of the present disclosure.

[0016] FIG. 6 is a diagrammatic schematic view of a photoacoustic IVUS
transducer according to some embodiments of the present disclosure.

[0017] FIG. 7A is a diagrammatic schematic view of a portion of a
photoacoustic IVUS system in a transmit mode according to some
embodiments of the present disclosure.

[0018] FIG. 7B is a diagrammatic schematic view of a portion of a
photoacoustic IVUS system in a receive mode according to some embodiments
of the present disclosure.

[0019] FIG. 8 is a diagrammatic schematic view of a portion of a
multi-modality optical system according to some embodiments of the
present disclosure.

[0020] FIG. 9 is a functional block diagram of portions of the medical
system of FIGS. 1A, 1B, and 1C according to some embodiments of the
present disclosure.

[0021] FIG. 10 is a functional block diagram of portions of the medical
system of FIGS. 1A, 1B, and 1C including a user interface component for
configuring the display of medical sensing data according to some
embodiments of the present disclosure.

[0022] FIG. 11 is a diagram of an exemplary user interface for customizing
the display of multi-modality medical data according to some embodiments
of the present disclosure.

[0023] FIG. 12 is a diagram of an exemplary user interface for customizing
the display of characterized tissue according to some embodiments of the
present disclosure.

[0024] FIG. 13 is a flow diagram of a method of collecting medical sensing
data based on a display attribute according to some embodiments of the
present disclosure.

[0025] FIG. 14 is a flow diagram of a method of processing and displaying
medical sensing data based on a display attribute according to some
embodiments of the present disclosure.

[0026] FIG. 15 is a flow diagram of a method of performing tissue
characterization based on a display attribute according to some
embodiments of the present disclosure.

[0027] FIG. 16 is a flow diagram of a method of locating a structure
within a vessel according to some embodiments of the present disclosure.

[0028] FIG. 17 is a flow diagram of a method of evaluating a vessel
according to some embodiments of the present disclosure.

[0029] FIG. 18 is a flow diagram of a method of displaying medical data by
simulating pullback of an intravascular sensing device according to some
embodiments of the present disclosure.

DETAILED DESCRIPTION

[0030] For the purposes of promoting an understanding of the principles of
the present disclosure, reference will now be made to the embodiments
illustrated in the drawings, and specific language will be used to
describe the same. It is nevertheless understood that no limitation to
the scope of the disclosure is intended. Any alterations and further
modifications to the described devices, systems, and methods, and any
further application of the principles of the present disclosure are fully
contemplated and included within the present disclosure as would normally
occur to one skilled in the art to which the disclosure relates. In
particular, it is fully contemplated that the features, components,
and/or steps described with respect to one embodiment may be combined
with the features, components, and/or steps described with respect to
other embodiments of the present disclosure. For the sake of brevity,
however, the numerous iterations of these combinations will not be
described separately.

[0031] FIGS. 1A, 1B, and 1C are schematic drawings depicting a medical
system including an invasive intravascular system in various applications
according to some embodiments of the present disclosure. In general, the
medical system 100 may be a single modality medical system or a
multi-modality medical system. In that regard, a multi-modality medical
system provides for coherent integration and consolidation of multiple
forms of acquisition and processing elements designed to be sensitive to
a variety of methods used to acquire and interpret human biological
physiology and morphological information and/or coordinate treatment of
various conditions.

[0032] With reference to FIG. 1A, the imaging system 101 is an integrated
device for the acquisition, control, interpretation, and display of one
or more modalities of medical sensing data. Accordingly, in some
embodiments, the imaging system 101 is a single modality imaging system,
such as an IVUS imaging system, whereas, in some embodiments, the imaging
system 101 is a multi-modality imaging system. In one embodiment, the
imaging system 101 includes a computer system with the hardware and
software to acquire, process, and display medical imaging data, but, in
other embodiments, the imaging system 101 includes any other type of
computing system operable to process medical data. In the embodiments in
which the imaging system 101 includes a computer workstation, the system
includes a processor such as a microcontroller or a dedicated central
processing unit (CPU), a non-transitory computer-readable storage medium
such as a hard drive, random access memory (RAM), and/or compact disk
read only memory (CD-ROM), a video controller such as a graphics
processing unit (GPU), and/or a network communication device such as an
Ethernet controller and/or wireless communication controller. In that
regard, in some particular instances, the imaging system 101 is
programmed to execute steps associated with the data acquisition and
analysis described herein. Accordingly, it is understood that any steps
related to data acquisition, data processing, instrument control, and/or
other processing or control aspects of the present disclosure may be
implemented by the imaging system 101 using corresponding instructions
stored on or in a non-transitory computer readable medium accessible by
the processing system. In some instances, the imaging system 101 is
portable (e.g., handheld, on a rolling cart, etc.). Further, it is
understood that in some instances imaging system 101 comprises a
plurality of computing devices. In that regard, it is particularly
understood that the different processing and/or control aspects of the
present disclosure may be implemented separately or within predefined
groupings using a plurality of computing devices. Any divisions and/or
combinations of the processing and/or control aspects described below
across multiple computing devices are within the scope of the present
disclosure.

[0033] In the illustrated embodiment, the medical system 100 is deployed
in a catheter lab 102 having a control room 104, with the imaging system
101 being located in the control room. In other embodiments, the imaging
system 101 may be located elsewhere, such as in the catheter lab 102, in
a centralized area in a medical facility, or at an off-site location
accessible over a network. For example, the imaging system 101 may be a
cloud-based resource. The catheter lab 102 includes a sterile field
generally encompassing a procedure area, whereas the associated control
room 104 may or may not be sterile depending on the requirements of a
procedure and/or health care facility. The catheter lab and control room
may be used to perform on a patient any number of medical sensing
procedures such as angiography, intravascular ultrasound (IVUS),
photoacoustic IVUS, forward looking IVUS (FL-IVUS), virtual histology
(VH), intravascular photoacoustic (IVPA) imaging, pressure determination,
optical pressure determination, a fractional flow reserve (FFR)
determination, a coronary flow reserve (CFR) determination, optical
coherence tomography (OCT), computed tomography, intracardiac
echocardiography (ICE), forward-looking ICE (FLICE), intravascular
palpography, transesophageal ultrasound, or any other medical sensing
modalities known in the art. Further, the catheter lab and control room
may be used to perform one or more treatment or therapy procedures on a
patient such as radiofrequency ablation (RFA), cryotherapy, atherectomy
or any other medical treatment procedure known in the art. For example,
in catheter lab 102 a patient 106 may be undergoing a multi-modality
procedure either as a single procedure or multiple procedures. In any
case, the catheter lab 102 includes a plurality of medical instruments
including medical sensing devices that collect medical sensing data in
various different medical sensing modalities from the patient 106.

[0034] In the illustrated embodiment of FIG. 1A, instruments 108 and 110
are medical sensing devices that may be utilized by a clinician to
acquire medical sensing data about the patient 106. In a particular
instance, the device 108 collects medical sensing data in one modality,
and the device 110 collects medical sensing data in a different modality.
For instance, the instruments may each collect one of pressure, flow
(velocity), images (including images obtained using ultrasound (e.g.,
IVUS), OCT, thermal, and/or other imaging techniques), temperature,
and/or combinations thereof. In some embodiments, device 108 and 110
collect medical sensing data in different versions of similar modalities.
For example, in one such embodiment, device 108 collects pressure data,
and device 110 collects FFR (a pressure-based measurement) data. In
another such embodiment, device 108 collects 20 MHz IVUS data, and device
110 collects 40 MHz IVUS data. Accordingly, the devices 108 and 110 may
be any form of device, instrument, or probe sized and shaped to be
positioned within a vessel, attached to an exterior of the patient, or
scanned across a patient at a distance.

[0035] In the illustrated embodiment of FIG. 1A, instrument 108 is an IVUS
catheter 108 that may include one or more sensors such as a phased-array
transducer to collect IVUS sensing data. In some embodiments, the IVUS
catheter 108 may be capable of multi-modality sensing such as IVUS and
IVPA sensing. Further, in the illustrated embodiment, the instrument 110
is an OCT catheter 110 that may include one or more optical sensors
configured to collect OCT sensing data. In some instances, an IVUS
patient interface module (PIM) 112 and an OCT PIM 114, respectively,
couple the IVUS catheter 108 and OCT catheter 110 to the imaging system
101. In particular, the IVUS PIM 112 and the OCT PIM 114 are operable to
receive medical sensing data collected from the patient 106 by the IVUS
catheter 108 and OCT catheter 110, respectively, and are operable to
transmit the received data to the imaging system 101 in the control room
104. In one embodiment, the PIMs 112 and 114 include analog to digital
(A/D) converters and transmit digital data to the imaging system 101,
however, in other embodiments, the PIMs transmit analog data to the
processing system. In one embodiment, the IVUS PIM 112 and OCT PIM 114
transmit the medical sensing data over a Peripheral Component
Interconnect Express (PCIe) data bus connection, but, in other
embodiments, they may transmit data over a USB connection, a Thunderbolt
connection, a FireWire connection, or some other high-speed data bus
connection. In other instances, the PIMs may be connected to the imaging
system 101 via wireless connections using IEEE 802.11 Wi-Fi standards,
Ultra Wide-Band (UWB) standards, wireless FireWire, wireless USB, or
another high-speed wireless networking standard.

[0036] Additionally, in the medical system 100, an electrocardiogram (ECG)
device 116 is operable to transmit electrocardiogram signals or other
hemodynamic data from patient 106 to the imaging system 101. In some
embodiments, the imaging system 101 may be operable to synchronize data
collected with the catheters 108 and 110 using ECG signals from the ECG
116. Further, an angiogram system 117 is operable to collect x-ray,
computed tomography (CT), or magnetic resonance images (MRI) of the
patient 106 and transmit them to the imaging system 101. In one
embodiment, the angiogram system 117 is communicatively coupled to the
processing system of the imaging system 101 through an adapter device.
Such an adaptor device may transform data from a proprietary third-party
format into a format usable by the imaging system 101. In some
embodiments, the imaging system 101 is operable to co-register image data
from angiogram system 117 (e.g., x-ray data, MRI data, CT data, etc.)
with sensing data from the IVUS and OCT catheters 108 and 110. As one
aspect of this, the co-registration may be performed to generate
three-dimensional images with the sensing data.

[0037] A bedside controller 118 is also communicatively coupled to the
imaging system 101 and provides user control of the particular medical
modality (or modalities) being used to diagnose the patient 106. In the
current embodiment, the bedside controller 118 is a touch screen
controller that provides user controls and diagnostic images on a single
surface. In alternative embodiments, however, the bedside controller 118
may include both a non-interactive display and separate controls such as
physical buttons and/or a joystick. In the integrated medical system 100,
the bedside controller 118 is operable to present workflow control
options and patient image data in graphical user interfaces (GUIs). As
will be described in greater detail in association with FIG. 9, in some
embodiments, the bedside controller 118 includes a user interface (UI)
framework service through which workflows associated with multiple
modalities may execute. Thus, the bedside controller 118 may be capable
displaying workflows and diagnostic images for multiple modalities
allowing a clinician to control the acquisition of multi-modality medical
sensing data with a single interface device.

[0038] A main controller 120 in the control room 104 is also
communicatively coupled to the imaging system 101 and, as shown in FIG.
1A, is adjacent to catheter lab 102. In the current embodiment, the main
controller 120 is similar to the bedside controller 118 in that it
includes a touch screen and is operable to display a multitude of
GUI-based workflows corresponding to different medical sensing modalities
via a UI framework service executing thereon. In some embodiments, the
main controller 120 is used to simultaneously carry out a different
aspect of a procedure's workflow than the bedside controller 118. In
alternative embodiments, the main controller 120 includes a
non-interactive display and standalone controls such as a mouse and
keyboard.

[0039] The medical system 100 further includes a boom display 122
communicatively coupled to the imaging system 101. The boom display 122
may include an array of monitors, each capable of displaying different
information associated with a medical sensing procedure. For example,
during an IVUS procedure, one monitor in the boom display 122 may display
a tomographic view and one monitor may display a sagittal view.

[0040] Further, the multi-modality imaging system 101 is communicatively
coupled to a data network 125. In the illustrated embodiment, the data
network 125 is a TCP/IP-based local area network (LAN); however, in other
embodiments, it may utilize a different protocol such as Synchronous
Optical Networking (SONET), or may be a wide area network (WAN). The
imaging system 101 may connect to various resources via the network 125.
For example, the imaging system 101 may communicate with a Digital
Imaging and Communications in Medicine (DICOM) system 126, a Picture
Archiving and Communication System (PACS) 127, and a Hospital Information
System (HIS) 128 through the network 125. Additionally, in some
embodiments, a network console 130 may communicate with the
multi-modality imaging system 101 via the network 125 to allow a doctor
or other health professional to access the aspects of the medical system
100 remotely. For instance, a user of the network console 130 may access
patient medical data such as diagnostic images collected by
multi-modality imaging system 101, or, in some embodiments, may monitor
or control one or more on-going procedures in the catheter lab 102 in
real-time. The network console 130 may be any sort of computing device
with a network connection such as a PC, laptop, smartphone, tablet
computer, or other such device located inside or outside of a health care
facility.

[0041] Additionally, in the illustrated embodiment, medical sensing tools
in system 100 discussed above are shown as communicatively coupled to the
imaging system 101 via a wired connection such as a standard copper link
or a fiber optic link, but, in alternative embodiments, the tools may be
connected to the imaging system 101 via wireless connections using IEEE
802.11 Wi-Fi standards, Ultra Wide-Band (UWB) standards, wireless
FireWire, wireless USB, or another high-speed wireless networking
standard.

[0042] One of ordinary skill in the art would recognize that the medical
system 100 described above is simply an example embodiment of a system
that is operable to collect diagnostic data associated with a plurality
of medical modalities. In alternative embodiments, different and/or
additional tools may be communicatively coupled to the imaging system 101
so as to contribute additional and/or different functionality to the
medical system 100.

[0043] With reference now to FIG. 1B, an application of the medical system
100 includes a coronary catheterization procedure. In a coronary
catheterization procedure, a medical sensing instrument including a
sensing catheter 150 is passed into a blood vessel of the heart 152 via
the aorta 154. In some embodiments, a guide wire 156 is first advanced
into the heart 152 through a large peripheral artery leading into the
aorta 154. Once the guide wire 156 is properly located, a guide catheter
158 is advanced over the guide wire. The sensing catheter 150 is then
directed into place by traveling over the guide wire 156 and inside the
guide catheter 158. In the illustrated embodiment, the distal tip of the
sensing catheter 150 is advanced until it is positioned in the left
coronary artery 160. The sensing catheter 150 is activated, and signals
are passed between the catheter 150 and components of the system 100 such
as the PIM 112 and/or the imaging system 101 of FIG. 1A. In the example
of an IVUS sensing catheter 150, signals sent from the IVUS PIM 112 to
one or more ultrasound transducers cause the transducers to emit a
specified ultrasonic waveform. Portions of the ultrasonic waveform are
reflected by the surrounding vasculature and received by a one or more
receiving transducers of the catheter 150. The resulting echo signals are
amplified for transmission to the IVUS PIM 112. In some instances, the
PIM 112 amplifies the echo data, performs preliminary pre-processing of
the echo data, and/or retransmits the echo data to the imaging system
101. The imaging system 101 aggregates and assembles the received echo
data to create an image of the vasculature for display.

[0044] In some exemplary applications, the IVUS sensing catheter 150 is
advanced beyond the area of the vascular structure to be imaged and
pulled back as the transducers are operating, thereby exposing and
imaging a longitudinal portion of the vessel. To ensure a constant
velocity, a pullback mechanism is used in some applications. A typical
withdraw velocity is 0.5 mm/s, although other rates are possible based on
beam geometry, sample speed, and the processing power of the system. In
some embodiments, the catheter 150 includes an inflatable balloon
portion. As part of a treatment procedure, the device may be positioned
adjacent to a stenosis (narrow segment) or an obstructing plaque within
the vascular structure and inflated in an attempt to widen the restricted
area.

[0045] With reference now to FIG. 1C, another application of the medical
system 100 includes a renal catheterization procedure. In a renal
catheterization procedure, the sensing catheter 170 is passed into a
blood vessel of the kidneys 172 via the aorta. This may involve first
advancing a guide wire and/or guide catheter and using the guide
device(s) to control the advance of the sensing catheter 170. In the
illustrated embodiment, the distal tip of the sensing catheter 170 is
advanced until it is located in the right renal artery 174. Then, the
sensing catheter 170 is activated and signals are passed between the
catheter 170 and components of the system 100 such as the PIM 112 and/or
the imaging system 101 of FIG. 1A. In the example of an IVUS sensing
catheter 170, the signals contain echo data transmitted from the catheter
170 to the imaging system 101 by way of the IVUS PIM 112. The structures
of the renal vasculature differ from those of the cardiac vasculature.
Vessel diameters, tissue types, and other differences may mean that
operating parameters suited to cardiac catheterization are less well
suited to renal catheterization and vice versa. Furthermore, renal
catheterization may target different structures, seeking to image the
renal adventitia rather than arterial plaques, for example. For these
reasons and more, the imaging system 101 may support different operating
parameters for different applications such as cardiac and renal imaging.
Likewise, the concept may be applied to any number of anatomical
locations and tissue types, including without limitation, organs
including the liver, heart, kidneys, gall bladder, pancreas, lungs;
ducts; intestines; nervous system structures including the brain, dural
sac, spinal cord and peripheral nerves; the urinary tract; as well as
valves within the blood or other systems of the body.

[0046] FIG. 2 is a diagrammatic schematic view of a medical sensing system
200 according to some embodiments of the present disclosure. The medical
sensing system 200 is suitable for use as a standalone system or as part
of a larger medical imaging system including the medical system 100 of
FIGS. 1A, 1B, and 1C. In that regard, elements of the sensing system 200
may be incorporated into elements of medical system 100. In alternate
embodiments, elements of the sensing system 200 are distinct from and are
in communication with elements of the medical system 100.

[0047] The medical sensing system 200 includes an elongate member 202. As
used herein, "elongate member" or "flexible elongate member" includes at
least any thin, long, flexible structure that can be inserted into the
vasculature of a patient. While the illustrated embodiments of the
"elongate members" of the present disclosure have a cylindrical profile
with a circular cross-sectional profile that defines an outer diameter of
the flexible elongate member, in other instances all or a portion of the
flexible elongate members may have other geometric cross-sectional
profiles (e.g., oval, rectangular, square, elliptical, etc.) or
non-geometric cross-sectional profiles. Flexible elongate members
include, for example, guide wires and catheters. In that regard,
catheters may or may not include a lumen extending along its length for
receiving and/or guiding other instruments. If the catheter includes a
lumen, the lumen may be centered or offset with respect to the
cross-sectional profile of the device.

[0048] Elongate member 202 includes sensors (e.g., sensors 204, 206, 208,
and 210) disposed along the length of the member 202. In some
embodiments, the elongate member 202 includes one or more sensors (e.g.,
sensor 212) disposed at the distal end. In various embodiments, sensors
204, 206, 208, 210, and 212 correspond to sensing modalities such as
flow, optical flow, IVUS, photoacoustic IVUS, FL-IVUS, pressure, optical
pressure, fractional flow reserve (FFR) determination, coronary flow
reserve (CFR) determination, OCT, transesophageal echocardiography,
image-guided therapy, other suitable modalities, and/or combinations
thereof. In an exemplary embodiment, sensors 204 and 208 are IVUS
ultrasound transceivers, sensors 206 and 210 are fluid flow sensors, and
sensor 212 is a pressure sensor. In another embodiment, sensors 204, 206,
208, and 210 are pressure sensors and sensor 212 is an FL-IVUS
transceiver. Other embodiments incorporate other combinations of sensors,
and no particular sensor or combination of sensors is required for any
particular embodiment.

[0049] The electronic, optical, and/or electro-optical sensors,
components, and associated communication lines are sized and shaped to
allow for the diameter of the flexible elongate member 202 to be very
small. For example, the outside diameter of the elongate member 202, such
as a guide wire or catheter, containing one or more electronic, optical,
and/or electro-optical components as described herein is between about
0.0007'' (0.0178 mm) and about 0.118'' (3.0 mm), with some particular
embodiments having outer diameters of approximately 0.014'' (0.3556 mm)
and approximately 0.018'' (0.4572 mm)). As such, the flexible elongate
members 202 incorporating the electronic, optical, and/or electro-optical
component(s) of the present application are suitable for use in a wide
variety of lumens within a human patient besides those that are part or
immediately surround the heart, including veins and arteries of the
extremities, renal arteries, blood vessels in and around the brain, and
other lumens.

[0050] The distal end of the elongate member 202 is advanced through a
vessel 214. Vessel 214 represents fluid filled or surrounded structures,
both natural and man-made, within a living body and can include for
example, but without limitation, structures such as: organs including the
liver, heart, kidneys, gall bladder, pancreas, lungs; ducts; intestines;
nervous system structures including the brain, dural sac, spinal cord and
peripheral nerves; the urinary tract; as well as valves within the blood
or other systems of the body. In addition to natural structures, elongate
member 202 may be used to examine man-made structures such as, but
without limitation, heart valves, stents, shunts, filters and other
devices positioned within the body, for example, a guide wire or guide
catheter.

[0051] When the sensors are active, a communications channel, such as an
optical fiber, a conductor bundle, and/or a wireless transceiver, present
in the elongate member 202 carries sensor data to a patient interface
monitor (PIM) 216 coupled to the proximal end of the elongate member 202.
The PIM 216 may be substantially similar to the IVUS PIM 112 and/or OCT
PIM 114 disclosed with reference to FIG. 1A. For example, the PIM 216 is
operable to receive medical sensing data collected using the sensors and
is operable to transmit the received data to a processing system 218. In
some embodiments, the PIM 216 performs preliminary processing of the
sensing data prior to transmitting the data to the processing system 218.
In examples of such embodiments, the PIM 216 performs amplification,
filtering, time-stamping, identification, and/or aggregating of the data.
The PIM 216 also transfers data such as commands from the processing
system 218 to the sensors of the elongate member 202. In an exemplary
embodiment, these commands include commands to enable and disable sensors
and/or to configure modes of operation for individual sensors. In some
embodiments, the PIM 216 also supplies power to drive The PIM 216 is
communicatively coupled to the processing system 218, which the operation
of the sensors.

[0052] governs sensor operation and data acquisition, processing,
interpretation, and display. In many respects, the processing system 218
is substantially similar to the imaging system 101 of FIG. 1A. In that
regard, the processing system 218 receives sensor data from the sensors
of the elongate member 202 via the PIM 216, processes the sensor data to
render it suitable for display, and presents the processed sensor data at
a user display 220.

[0053] In many embodiments, the medical sensing system 200 leverages the
ability of the processing system 218 to support an increased number of
sensors. In some such embodiments, this allows operators to locate
vascular abnormalities or other structures that are not visible using
external imaging. In one such embodiment, a series of measurements is
taken along the length of the elongate member 202 in order to detect the
structure of interest without necessarily relocating the elongate member
202. This may take the form of a virtual pullback. Once the structure of
interest is located, detailed measurements may be taken of the
surrounding area. In this way, the system 200 provides detailed analysis
of the surrounding vasculature without a physical pullback and/or without
exchanging devices.

[0054] FIG. 3 is a diagrammatic schematic view of a portion of an
electromechanical medical sensing system 300 according to some
embodiments of the present disclosure. The system 300 may be
substantially similar to the sensing system 200 disclosed with reference
to FIG. 2. In that regard, the system 300 incorporates multiple sensors
(e.g., sensors 304, 306, and 308) in the distal end of an elongate member
302 of the sensing system 300. While, in the interest of clarity, only
three sensors are illustrated, further embodiments incorporate any number
of sensors including embodiments with 4, 8, 16, 32, and more sensors. The
sensors 304, 306, and 308 correspond to one or more sensing modalities
such as flow, optical flow, IVUS, photoacoustic IVUS, FL-IVUS, pressure,
optical pressure, FFR determination, CFR determination, OCT,
transesophageal echocardiography, image-guided therapy, and/or other
suitable modalities. For example, in some embodiments, sensors 304, 306,
and 308 include IVUS transducers. In that regard, the sensors may include
piezoelectric micromachine ultrasound transducers (PMUTs), capacitive
micromachined ultrasound transducers (CMUT), piezoelectric transducers
(PZTs), and/or combination thereof. U.S. Pat. No. 6,238,347, entitled
"ULTRASONIC TRANSDUCER ARRAY AND METHOD OF MANUFACTURING THE SAME," U.S.
Pat. No. 6,641,540, entitled "MINIATURE ULTRASOUND TRANSDUCER," U.S. Pat.
No. 7,226,417, entitled "HIGH RESOLUTION INTRAVASCULAR ULTRASOUND
TRANSDUCER ASSEMBLY HAVING A FLEXIBLE SUBSTRATE," and U.S. Pat. No.
7,914,458, entitled "CAPACITIVE MICROFABRICATED ULTRASOUND
TRANSDUCER-BASED INTRAVASCULAR ULTRASOUND PROBES," disclose IVUS
transducers in more detail and are herein incorporated by reference.
Examples of commercially available products that include suitable IVUS
transducers include, without limitation, the Eagle Eye® series of
IVUS catheters, the Revolution® IVUS catheter, and the Visions®
series of IVUS catheters, each available from Volcano Corporation. For
the purposes of this disclosure, such transducers are referred to as
"electromechanical transducers" due to the electrical interface and
electromechanical operation. This is in contrast to the optical interface
and photoacoustic operation of photoacoustic transducers disclosed in
detail below.

[0055] As another example, in some embodiments, sensors 304, 306, and 308
include pressure sensors and may take the form of a piezo-resistive
pressure sensor, a piezoelectric pressure sensor, a capacitive pressure
sensor, an electromagnetic pressure sensor, a fluid column (the fluid
column being in communication with a fluid column sensor that is separate
from the instrument and/or positioned at a portion of the instrument
proximal of the fluid column), an optical pressure sensor, and/or
combinations thereof. In some instances, one or more features of the
pressure sensor are implemented as a solid-state component manufactured
using semiconductor and/or other suitable manufacturing techniques.
Examples of commercially available guide wire products that include
suitable pressure sensors include, without limitation, the PrimeWire
PRESTIGE® pressure guide wire, the PrimeWire® pressure guide
wire, and the ComboWire® XT pressure and flow guide wire, each
available from Volcano Corporation.

[0056] The sensors 304, 306, and 308 are distributed along the distal end
of the elongate member 302 and are connected to a transmission line
bundle 310 that terminates in a PIM coupler (not illustrated) at a
proximal end of the system 300. The transmission line bundle 310 provides
an electrical interface between a PIM and sensors 304, 306, and 308, and
contains any number of conductors, including embodiments with 2, 3, 4, 6,
7, and 8 total conductors, in any arrangement. As the sensors 304, 308,
and 308 are coupled to an electrical interface (e.g., transmission line
bundle 310) and are electrically operated, they are referred to as
"electromechanical sensors" for the purposes of this disclosure.

[0057] In contrast to the electrical interface of system 300, FIG. 4 is a
diagrammatic schematic view of a portion of an optical sensing system 400
having an optical interface according to some embodiments of the present
disclosure. The system 400 may be substantially similar to the sensing
system 200 disclosed with reference to FIG. 2. In that regard, the system
400 incorporates multiple optical sensors (e.g., sensors 404, 406, and
408) in the distal end of an elongate member 402 of the sensing system
400. While, in the interest of clarity, only three sensors are
illustrated, further embodiments incorporate any number of sensors
including embodiments with 4, 8, 16, 32, and more sensors. The sensors
404, 406, and 408 correspond to sensing modalities such as flow, optical
flow, IVUS, photoacoustic IVUS, FL-IVUS, pressure, optical pressure, FFR
determination, CFR determination, OCT, transesophageal echocardiography,
image-guided therapy, and/or other suitable modalities. As an example, in
some embodiments, sensors 404, 406, and 408 include photoacoustic IVUS
transducers. U.S. Pat. No. 7,245,789, entitled "SYSTEMS AND METHODS FOR
MINIMALLY-INVASIVE PHOTOACOUSTIC IMAGING," U.S. Pat. No. 6,659,957,
entitled "PHOTOACOUSTIC IMAGING DEVICE," and U.S. patent application Ser.
No. 12/571,724, entitled "OPTICAL ULTRASOUND RECEIVER, disclose
photoacoustic IVUS devices in detail and are herein incorporated in their
entirety. Furthermore, additional suitable photoacoustic IVUS transducers
are disclosed below with reference to FIGS. 6-9.

[0058] As a further example, in some embodiments, sensors 404, 406, and
408 include optical pressure sensors. U.S. Pat. No. 7,689,071, entitled
"FIBER OPTIC PRESSURE SENSOR FOR CATHETER USE," U.S. Pat. No. 8,151,648,
entitled "ULTRA-MINIATURE FIBER-OPTIC PRESSURE SENSOR SYSTEM AND METHOD
OF FABRICATION," and U.S. application Ser. No. 13/415,514, entitled
"MINIATURE HIGH SENSITIVITY PRESSURE SENSOR," disclose optical pressure
sensors in detail and are herein incorporated in their entirety.

[0059] Sensors 404, 406, and 408 are connected to a fiber core 410 that
optically couples the sensors to a PIM (not shown). In some embodiments,
the optical fiber core 410 is configured for spatial multiplexing of
sensor data. Spatial multiplexing divides a common conduit such as a
fiber core 410 into physical regions, where each physical region of the
conduit is reserved for a particular device. In one such embodiment, the
fiber core 410 comprises multiple strands of optical fibers, and each
strand or strand group is exclusively coupled to a single sensor. Spatial
multiplexing allows the PIM to address individual sensors by transmitting
and receiving data using the corresponding strand or strand group.

[0060] In some embodiments, sensor data is wavelength division
multiplexed. Wavelength division optical multiplexing assigns each data
channel a unique portion of the spectrum. Sufficient spacing is allocated
between channels to reduce crosstalk and to allow for manufacturing
variability. The data channels can then be transmitted concurrently over
a common conduit, such as fiber core 410, without interference. In such
embodiments, optical filters or gratings are located along the length of
the fiber core 410 and are tuned to demultiplex the appropriate signals
and direct them towards the corresponding sensor. Wavelength division
multiplexing may be particularly useful for embodiments where the optical
fiber core 410 is rotated independently of the PIM, such as rotational
IVUS and rotational OCT, as the transmission of data does not rely on an
alignment of fiber core strands relative to the PIM. As a further
example, in some embodiments, the sensor data is time-division
multiplexed, although no particular multiplexing scheme is required for
any particular embodiment.

[0061] FIGS. 5A and 5B are diagrammatic schematic views of a medical
sensing device used in a catheterization procedure 500 according to some
embodiments of the present disclosure. With reference first to FIG. 5A,
an elongate member 502 of the medical sensing device is advanced into a
vessel 504. The elongate member 502 is substantially similar to those
disclosed with reference of FIGS. 2-4. In that regard, the elongate
member incorporates sensors 506 (including sensors 506a-d) in the distal
end of the elongate member 502. The sensors 506 correspond to one or more
sensing modalities such as flow, optical flow, IVUS, photoacoustic IVUS,
FL-IVUS, pressure, optical pressure, FFR determination, CFR
determination, OCT, transesophageal echocardiography, image-guided
therapy, and/or other suitable modalities. Vessel 504 represents fluid
filled or surrounded structures, both natural and man-made, within a
living body and can include for example, but without limitation,
structures such as: organs including the liver, heart, kidneys, gall
bladder, pancreas, lungs; ducts; intestines; nervous system structures
including the brain, dural sac, spinal cord and peripheral nerves; the
urinary tract; as well as valves within the blood or other systems of the
body. In addition to natural structures, elongate member 502 may be used
to examine man-made structures such as, but without limitation, heart
valves, stents, shunts, filters and other devices positioned within the
body, for example, a guide wire or guide catheter.

[0062] Many cardiovascular structures of interest cannot be accurately
located using external means. In many other applications, while the
location of the both structure of interest and the elongate member 502
can be determined generally, achieving the proper alignment of the two
proves challenging. Therefore, it may be advantageous to use the array of
sensors 506 arranged along the longitudinal length of the elongate member
502 to determine the location of the structure of interest. In the
illustrated embodiment, the elongate member 502 is advanced into the
vessel 504 until it is in the general area of structures 508, 510, and
512. In various applications, structures of interest include
bifurcations, stenoses, plaques, vascular dissections, lesions, stents,
and/or other suitable venous morphology. Once in position, a series of
measurements are obtained from which the vascular structure can be
detected.

[0063] For example, in some embodiments, sensors 506 include pressure
sensors, and a series of fractional flow reserve ratios are calculated.
FFR is a currently accepted technique for assessing the severity of a
stenosis in a blood vessel, including ischemia-causing lesions, and may
be used to determine other types of vascular structures. FFR is a
calculation of the ratio of a distal pressure measurement (taken on the
distal side of the stenosis) relative to a proximal pressure measurement
(taken on the proximal side of the stenosis). FFR provides an index of
stenosis severity that allows determination as to whether the blockage
limits blood flow within the vessel to an extent that treatment is
required. The normal value of FFR in a healthy vessel is 1.00, while
values less than about 0.80 are generally deemed significant and require
treatment. Further measurements such as Instant Wave-Free Ratio®
Functionality data (iFR® Functionality) (both trademarks of Volcano
Corp.) and those disclosed in U.S. patent application Ser. No.
13/460,296, entitled "DEVICES, SYSTEMS, AND METHODS FOR ASSESSING A
VESSEL," which discloses the use of pressure ratios that are available
without a hyperemic agent, are also suitable for use in some embodiments.
From the iFR® and/or FFR data, structures such as stenoses can be
inferred. For example, in some embodiments, an FFR below a threshold
(e.g., 0.80) suggests that a structure such as a stenosis lies between
the proximal and the distal sensors 506. Thus, the location of the
stenosis can be inferred from the known location of the sensors 506 on
either side of where the FFR measurement drops below the threshold.

[0064] In other exemplary embodiments, sensors 506 such as IVUS
transducers or OCT transceivers are used to take cross-sectional or
forward-looking views of the vessel 504 along the length of the elongate
member 502. In such embodiments, the location of vascular structures
(e.g., structures 508, 510, and 512) may be determined by examining
differences in images across sensors, by a tissue characterization
process such as the process disclosed in detail below, and/or by other
diagnostic examination of the data.

[0065] In further exemplary embodiments, other combinations of sensors 506
and modalities are used to locate vascular structures, and one of skill
in the art will recognize that the location of a structure can be
determined using a variety of sensors 506 and modalities without
departing from the spirit of the present disclosure.

[0066] In addition to locating structures, the data collected by the
sensors 506 can be utilized for diagnostic purposes. For example, in one
embodiment, the sensors 506 include pressure sensors, and a series of FFR
determinations are taken along the length of the member 502. In the
example, the data indicates multiple plaque stenoses (e.g., structures
510 and 512). Therefore, an FFR ratio is calculated to determine the
combined effect using a proximal sensor proximal to all of the plaques
and a distal sensor distal to all of the plaques (e.g., sensor 506a and
506d). Additional FFR ratios are also calculated to determine the
individual effect of each plaque. These individual FFR ratios are
calculated using sensors located proximal and distal to each plaque such
that the sensors are approximately between each plaque and the next
(e.g., sensors 506a and 506b for structure 510 and sensors 506c and 506d
for structure 512). In this way, the operator can distinguish stenoses
that are individually benign but collectively acute, and can determine
which obstructions have the largest overall contribution.

[0067] Further embodiments utilize other multi-site determinations to
evaluate overall vascular health. For example, in one such embodiment,
the elongate member 502 is used to perform a virtual pullback. In
response to a user command, the data collected using the sensors 506 may
be presented to the user in sequence. Stepping through the sensors in
order of location simulates a pullback of a single sensor through the
vessel 504 without actually withdrawing the elongate member 502. This
allows subsequent measurements of the simulated pullback to be performed
without repositioning the device.

[0068] Referring now to FIG. 5B, the elongate member 502, the incorporated
sensors 506, and the vessel 504 are substantially similar to those
disclosed with reference to FIG. 5A. However, the elongate member also
includes a detailed sensing region 514. Once a structure of interest is
located, the detailed sensing region 514 may be used to examine the
structure. The detailed sensing region 514 is maneuvered into position
adjacent to the structure (e.g., structure 512), and data is collected
using the associated sensors 506. In the illustrated embodiment, the
detailed sensing region 514 has tighter sensor spacing than the remainder
of the elongate member 502. In addition or in the alternative, the
detailed sensing region 514 may incorporate different types of sensors
that correspond to different modalities or sets of modalities. In some
embodiments, the sensors of the detailed sensing region have a higher
sensing resolution along the axial length of the elongate member 502 than
other sensors of the elongate member 502. In various further embodiments,
the detailed sensing region 514 has other sensing differences as compared
to the remainder of the elongate member 502. The detailed sensing region
514 allows for in depth sensing and analysis when desired, but reduces
device complexity, cost, and/or system requirements by limiting the
number of sensors 506 allocated for detailed analysis.

[0069] FIG. 6 is a diagrammatic schematic view of a photoacoustic IVUS
transducer 600 according to some embodiments of the present disclosure.
The illustrated transducer 600 is suitable for use in a sensing device
such as instruments 108 and 110 of FIG. 1A, elongate member 202 of FIG.
2, and/or elongate member 402 of FIG. 4. Furthermore, because the
transducer 600 includes an ultrasound membrane and a reflective etalon
structure arranged in a vertical stack, the device is particularly well
suited for use in an end-looking photoacoustic IVUS sensing device.

[0070] The transducer 600 is physically coupled to a fiber core 410 that
acts as a conduit for transmitting optical signals along a longitudinal
length of a sensing device such as a catheter, guide catheter or guide
wire. The fiber core 410 communicatively couples the transducer 600 at a
distal portion of the device to a PIM at a proximal portion. The
transducer 600 itself includes a receiver portion 604 and a transmitter
portion 606 coupled to the fiber core 410 via a transparent substrate
602, which offers structural support of the transducer 600 during
manufacturing, assembly, and/or operation. The receiver portion 604
includes an etalon 608, a form of sensor that can be optically probed to
determine the strength of ultrasound echoes acting on the etalon 608. The
etalon 608 includes two partially reflective mirrors (e.g., initial
mirror 610 and terminal minor 614) separated by a spacer layer 612. In an
exemplary embodiment, the distance between the initial minor 610 and the
terminal mirror 614 and likewise the thickness of the spacer layer 612 is
approximately 5.9 μm. In an exemplary embodiment, the thickness of
each of the initial minor 610 and the terminal minor 614 is approximately
30 nm. In some embodiments, both minors 610 and 614 have substantially
equivalent reflectivity. In some further embodiments, the terminal minor
614 has substantially higher reflectivity than the initial minor 610.

[0071] When a light source, such as a probing laser, is directed at the
etalon 608 as illustrated by arrow 616, a portion of the light energy is
reflected by the initial minor 610 as illustrated by arrow 618. This
defines the first of two optical paths. A second portion of the light
energy passes through initial mirror 610 and the spacer layer 612 and is
reflected by the terminal mirror 610 as illustrated by arrow 620. This
defines the second optical path. Differences in the optical paths affect
the phase of the two reflected signals relative to one another. These
differences may be measured by examining the interference pattern of the
reflected signals.

[0072] In an embodiment, both reflected signals are carried by the fiber
core 410 to the PIM (not illustrated) where the interference pattern is
analyzed. A baseline interference pattern is established representing a
state where negligible ultrasonic pressure is acting on the etalon 608.
As compressive and expansive forces, such as those caused by reflected
ultrasound echoes, are directed upon the etalon 608, the forces alter the
optical path and, thus, the interference pattern. In some embodiments,
the material of the spacer layer 612 exhibits a change in physical
dimension under stress. In some embodiments, the material of the spacer
layer 612 exhibits a change in refractive index under stress. Thus,
changes in the optical path can be a function of the distance between the
initial mirror 610 and terminal minor 610 and/or a function of the
refractive index of the spacer layer 612. Put another way, a change in
the refractive index of the spacer layer 612 can induce a change in
optical path length, even though the physical distance between minor 610
and mirror 614 has not substantially changed. The aforementioned changes
in the optical paths produce changes in the interference pattern, and, by
comparing subsequent interference patterns to the baseline, the PIM
obtains corresponding force measurements.

[0073] The transducer 600 also includes an emitter portion 606 disposed
above the receiver portion 604. The emitter portion includes an expansive
film 622 that, in various embodiments, is made of an elastic
biocompatible material such as one or more of polydimethylsiloxane
(PDMS), polyvinylidene fluoride (PVDF), and/or other suitable materials.
In one embodiment, a PDMS film 622 is formed to a thickness of
approximately 11 μm. The film 622 expands when heated with optical
energy such as laser energy. Rapid expansion and contraction caused by,
for example, a pulsed laser illustrated by arrow 624 causes the film 622
to generate an ultrasonic waveform. In an exemplary embodiment, the
pulsed laser produces a 25 nanosecond pulse with a 50 nanosecond rest to
allow the film 622 to cool and induces a 20 MHz ultrasound pulse. In some
embodiments, the mirrors 610 and 614 of the etalon 608 are adapted to
transmit energy from the pulsed laser through the mirrors to reach the
film 622 while reflecting energy from the probing laser. In some
embodiments, the mirrors 610 and 614 have an aperture 626 formed therein
to allow transmission of the pulsed laser through the etalon 608. An
exemplary aperture 626 is approximately 2 mm wide.

[0074] FIG. 7A is a diagrammatic schematic view of a portion of a
photoacoustic IVUS system 700 according to some embodiments of the
present disclosure. The illustrated system 700 is suitable for use in a
sensing device such as instruments 108 and 110 of FIG. 1A and may be
substantially similar to system 200 of FIG. 2 and/or system 400 of FIG.
4. In that regard, the photoacoustic IVUS system 700 has an elongate
member 702 that includes an optical fiber core 410. The elongate member
also includes two side-looking photoacoustic ultrasound transducers 706
and 708 disposed around the fiber core 410. Further embodiments
incorporate other numbers of transducers and may incorporate both
photoacoustic and electromechanical transducers.

[0075] The photoacoustic ultrasound transducers 706 and 708 each include a
pair of perpendicularly aligned fiber Bragg gratings (e.g., gratings 710
and 712 of transducer 706 and gratings 714 and 716 of transducer 708)
that form etalons 718 and 720. Each transducer also includes a blazed
(angled) fiber Bragg grating (e.g., gratings 722 and 724) that direct
light energy towards a diaphragm (e.g., diaphragms 726 and 728) of
expansive film such as one or more of polydimethylsiloxane (PDMS),
polyvinylidene fluoride (PVDF), and/or other suitable materials. The
fiber Bragg gratings 710, 712, 714, 716, 722, and 724 are configured to
reflect and transmit particular wavelengths of light. A uniform pitch
fiber Bragg grating reflects light within a narrowband frequency range
centered about a Bragg wavelength λ given by λ=2nΛ,
where n is the index of the fiber core 410 and Λ is the grating
period. Thus, by tuning the pitch of the fiber Bragg grating, the optical
response of the grating can be tuned. In particular, the pitch of the
fiber Bragg gratings may be tuned to demultiplex signals transmitted
along the fiber core 410 in a wavelength division multiplexing
communication scheme, as will be disclosed in more detail below. In
brief, tuned fiber Bragg gratings allow the independent control of each
transducer (e.g., transducers 706 and 708) over a multiplexed optical
channel.

[0076] FIG. 7A illustrates this independent control of transducers 706 and
708 in a transmit mode. The first blazed fiber Bragg grating 722 reflects
laser energy of a first wavelength. Because of the angle of the Bragg
grating, the reflected energy is directed towards the diaphragm 726 as
illustrated by arrow 730 where it heats the film of diaphragm 726 and
causes an ultrasonic impulse. In contrast, the first blazed fiber Bragg
grating 722 transmits, rather than reflects, laser energy of a second
wavelength. Accordingly, independent of the operation of the first
transducer 706, energy of the second wavelength is conducted along the
fiber core 410 as illustrated by arrow 732 until it reaches the second
blazed fiber Bragg grating 724. The pitch of the second grating 724 is
configured to reflect laser energy of the second wavelength towards the
film of the diaphragm 728 where it heats the diaphragm 728 and causes an
ultrasonic impulse. This concept is not limited to two transducers, and
in various exemplary embodiments 4, 8, 16, 32, and more transducers are
arranged on a common fiber core.

[0077] FIG. 7B is a diagrammatic schematic view of a portion of a
photoacoustic IVUS system 750 according to some embodiments of the
present disclosure. The illustrated system 750 is suitable for use in a
sensing device such as instruments 108 and 110 of FIG. 1A and may be
substantially similar to system 200 of FIG. 2 and/or system 400 of FIG.
4. The photoacoustic IVUS system 750 is substantially similar to system
700 disclosed with respect to FIG. 7A. In that regard, the system 750
includes an elongate member 702, a fiber optic core 410, and a
photoacoustic transducer 706 comprising perpendicular fiber Bragg
gratings 710 and 712, a blazed (angled) fiber Bragg grating 722, and a
diaphragm 726 substantially similar to those described with respect to
FIG. 7A.

[0078] FIG. 7B illustrates the operation of the transducer 706 in receive
mode. The perpendicular fiber Bragg gratings 710 and 712 form an etalon
718, which may be used to measure ultrasonic echo signals received by the
transducer 706. When a light source, such as a probing laser, is directed
at the etalon 718 as illustrated by arrow 752, a portion of the light
energy is reflected by the first fiber Bragg grating 710 as illustrated
by arrow 754. A second portion of the light energy passes through the
segment of the fiber core 410 between the first and second perpendicular
fiber Bragg gratings 710 and 712. The blazed fiber Bragg grating 722 does
not hinder the passage of this light energy as it is configured to
transmit light energy having the probing wavelength. This may be achieved
by configuring the pitch of the blazed fiber Bragg grating 722 as
disclosed above. Accordingly, the second portion of the light energy
continues through the fiber core 410 until it is reflected by the second
perpendicular grating 712 as indicated by arrow 756.

[0079] Differences in the optical paths affect the phase of the two
reflected signals relative to one another. These differences may be
measured by examining the interference pattern of the reflected signals.
In an embodiment, both reflected signals are carried by the fiber core
410 to the PIM (not illustrated) where the interference pattern is
analyzed. A baseline interference pattern is established representing a
state where negligible ultrasonic pressure is acting on the etalon 718.
As compressive and expansive forces, such as those caused by reflected
ultrasound echoes, are directed upon the etalon 718, the forces alter the
optical path and, thus, the interference pattern. By comparing subsequent
interference patterns to the baseline, corresponding force measurements
can be obtained. Differences in the optical paths can be a function of
the distance between the first perpendicular grating 710 and the second
perpendicular grating 712 as well as a function of the refractive index
of the fiber core 410 between the gratings 710 and 712. Thus, a change in
the refractive index of the fiber core 410 can induce a change in optical
path length, even though the physical distance between the gratings 710
and 712 has not substantially changed.

[0080] In some embodiments, multiple transducer etalons 718 are arranged
along a fiber core 410. In accordance with the principles disclosed
above, the gratings of each etalon 718 are configured to reflect a
wavelength unique to the transducer and to transmit wavelengths
characteristic of the other transducers. This allows the independent
measurement of ultrasonic echo data at any particular transducer by
probing the transducer with the characteristic wavelength and measuring
the resulting interference pattern. In various exemplary embodiments, 2,
4, 8, 16, 32, and more transducer etalons are arranged on a common fiber
core, each transducer being independently addressable via a unique
optical wavelength.

[0081] FIG. 8 is a diagrammatic schematic view of a portion of a
multi-modality optical system according to some embodiments of the
present disclosure. The illustrated system 800 is suitable for use in a
sensing device such as instruments 108 and 110 of FIG. 1A and may be
substantially similar to system 200 of FIG. 2 and/or system 400 of FIG.
4. Furthermore, the system 800 is substantially similar to the systems
700 and 750 disclosed with reference to FIGS. 7A and 7B. In that regard,
the system 800 includes photoacoustic transducers 706 and 708, which in
turn include perpendicular fiber Bragg gratings that form etalons and
blazed fiber Bragg gratings that direct light energy from a fiber core
410 towards elastic diaphragms.

[0082] The system 800 also includes one or more additional sensors
arranged along the system 800. These sensors may be located along the
longitudinal length of the system 800 such as sensor 802 and/or at the
tip of the system 800 such as sensor 804. In various embodiments, sensors
802 and 804 include ultrasound transducers, OCT sensors, pressure
sensors, flow sensors, and/or other suitable medical sensors and are
electrically and/or optically operated. In an exemplary embodiment,
sensor 802 includes an optical pressure sensor. In another exemplary
embodiment, sensor 804 includes an optical FL-IVUS transducer. Thus, the
system 800 incorporates a diverse array of sensors corresponding to a
wide assortment of modalities into a single sensing instrument.

[0083] With reference now to FIG. 9, illustrated is a functional block
diagram of portions of the medical system 100 of FIGS. 1A, 1B, and 1C,
including a processing framework 900 executing on some embodiments of the
imaging system 101. The processing framework 900 includes various
independent and dependent executable components that control the
operation of the imaging system 101, including the acquisition,
processing, and display of medical sensing data associated with one or
more modalities. In general, the processing framework 900 of imaging
system 101 is modular and extensible. That is, the framework 900 is
comprised of independent software and/or hardware components (or
extensions) respectively associated with different functions and medical
sensing modalities. This modular design allows the framework to be
extended to accommodate additional medical sensing modalities and
functionality without impacting existing functionality or requiring
changes to the underlying architecture. Further, an internal messaging
system facilitates independent data communication between modules within
the framework. In one instance, the processing framework 900 may be
implemented as computer-executable instructions stored on a
non-transitory computer-readable storage medium in the imaging system
101. In other instances, the processing framework 900 may be a
combination of hardware and software modules executing within with the
imaging system 101.

[0084] Generally, in the embodiment shown in FIG. 9, processing framework
900 includes a plurality of components that are configured to receive
medical sensing data from one or more medical sensing devices, process
the data, and output the data as diagnostic images via the main
controller 120, the bedside controller 118, or other graphical display
device. The framework 900 includes several system-level components that
manage the core system functions of the imaging system 101 and also
coordinate the plurality of modality-specific components. For instance,
the framework 900 includes a system controller 902 that coordinates
startup and shutdown of the plurality of executable components of the
processing framework 900, including hardware and software modules related
to acquisition and processing of patient diagnostic data. The system
controller 902 is also configured to monitor the state of components
executing within the framework 902, for instance, to determine if any
components have unexpectedly stopped executing. In addition, the system
controller 902 provides an interface through which other framework
components may obtain system configuration and status information.
Because the software framework 900 is modular, the system controller 902
is independent of the components within the framework that it manages so
that errors and changes made to components do not affect the execution or
structure of the system controller.

[0085] As mentioned above, the framework 900 is configured such that
various extensions may be added and removed without system architecture
changes. In certain embodiments, an extension executing within framework
900 may include a plurality of executable components that together
implement the full functionality of the extension. In such embodiments,
an extension may include an extension controller that is similar to the
system controller 902 that is operable to startup, shutdown, and monitor
the various executable components associated with the extension. For
example, upon system startup, the system controller 902 may start an
extension controller corresponding to a medical modality, and then the
extension controller may, in turn, start the executable components
associated with the modality. In one embodiment, extension controllers
may be unallocated until system controller 902 associates them with a
specific modality or other system task via parameters retrieved from a
configuration mechanism, such as a configuration file.

[0086] The processing framework 900 further includes a workflow controller
component 904 that is generally configured to govern the execution of the
executable components of the framework 902 during medical sensing
workflows. The workflow controller component 904 may govern workflows
executed by the processing framework 900 in various different manners.

[0087] The processing framework 900 further includes an event logging
component 906 that is configured to log messages received from various
components of the processing framework. For instance, during system
startup, the system controller 902 may send messages about the status of
components being started to the event logging component 906 which, in
turn, writes the messages to a log file in a standardized format.
Additionally, the processing framework 900 includes a resource arbiter
component 908 that is configured to manage the sharing of limited system
resources between various executable components of the framework 902
during multi-modality medical sensing and/or treatment workflows. For
example, during a multi-modality workflow, two or more components
associated with different modalities within the processing framework 902
may be vying for the same system resource such as a graphical display on
the main controller 120. The resource arbiter component 908 may
coordinate sharing of limited system resources in various manners such as
through a lock system, a queue system, or a hierarchical collision
management system.

[0088] In one embodiment, the system controller 902, workflow controller
component 904, event logging component 906, and resource arbiter
component 908 may be implemented as processor-executable software stored
on non-transitory, computer-readable storage media, but in alternative
embodiments, these components may be implemented as hardware components
such as special purpose microprocessors, Field Programmable Gate Arrays
(FPGAs), microcontrollers, graphics processing units (GPU), digital
signal processors (DSP). Alternatively, the components of the processing
framework may be implemented as a combination of hardware and software.
In certain embodiments in which executable components are implemented in
FPGAs, the system controller 902 may be configured to alter the
programmable logic within the FPGAs dynamically to implement various
functionality needed at the time. As an aspect of this, the imaging
system 101 may include one or more unassigned FPGAs that may be allocated
by the system controller during system startup. For instance, if upon
startup of the imaging system 101, the system controller detects an OCT
PIM and catheter coupled thereto, the system controller or an extension
controller associated with OCT functionality may dynamically transform
the programmable logic within one the unassigned FPGAs such that it
includes functionality to receive and/or process OCT medical data.

[0089] To facilitate intersystem communication between different hardware
and software components in the multi-modality imaging system 101, the
processing framework 900 further includes a message delivery component
910. In one embodiment, the message delivery component 910 is configured
to receive messages from components within the framework 902, determine
the intended target of the messages, and deliver the messages in timely
manner (i.e., the message delivery component is an active participant in
the delivery of messages). In such an embodiment, message metadata may be
generated by the sending component that includes destination information,
payload data (e.g., modality type, patient data, etc.), priority
information, timing information, or other such information. In another
embodiment, message delivery component 910 may be configured to receive
messages from components within the framework 902, temporarily store the
messages, and make the messages available for retrieval by other
components within the framework (i.e., the message delivery component is
a passive queue). In any case, the message delivery component 910
facilitates communication between executable components in the framework
900. For instance, the system controller 902 may utilize the message
delivery component 910 to inquire into the status of components starting
up during a system startup sequence, and then, upon the receiving status
information, utilize the message delivery component to transmit the
status information to the event logging component 906 so that it may be
written to a log file. Similarly, the resource arbiter component 908 may
utilize the message delivery component 910 to pass a resource token
between components requesting access to limited resources.

[0090] In one example embodiment in which the message delivery component
910 is a passive queue, components in the framework 900 may packetize
incoming medical sensing data into messages and then transmit the
messages to a queue on the message delivery component where they may be
retrieved by other components such as image data processing components.
Further, in some embodiments, the message delivery component 910 is
operable to make received messages available in a First-In-First-Out
(FIFO) manner, wherein messages that arrive on the queue first will be
removed from the queue first. In alternative embodiments, the message
delivery component 910 may make messages available in a different manner
for instance by a priority value stored in a message header. In one
embodiment, the message delivery component 910 is implemented in
random-access memory (RAM) in the imaging system 101, but, in other
embodiments, it may be implemented in non-volatile RAM (NVRAM), secondary
storage (e.g., magnetic hard drives, flash memory, etc.), or
network-based storage. Further, in one embodiment, messages stored on the
message delivery component 910 may be accessed by software and hardware
modules in imaging system 101 using Direct Memory Access (DMA).

[0091] The processing framework 902 may include a number of additional
system components that provide core system functionality including a
security component 912, a multi-modality case management (MMCM) component
914, and a database management component 916. In certain embodiments, the
security component 912 is configured to provide various security services
to the overall processing framework and to individual components. For
example, components implementing an IVUS data acquisition workflow may
utilize encryption application programming interfaces (APIs) exposed by
the security component 912 to encrypt IVUS data before it is transmitted
over a network connection. Further, the security component 912 may
provide other security services, such as system-level authentication and
authorization services to restrict access to the processing framework to
credentialed users and also to prevent the execution of untrusted
components within the extensible framework. The multi-modality case
management (MMCM) component 914 is configured to coordinate and
consolidate diagnostic data associated with a plurality of medical
modalities into a unified patient record that may be more easily managed.
Such a unified patient record may be more efficiently stored in a
database and may be more amenable to data archival and retrieval. In that
regard, the database management component 916 is configured to present
transparent database services to the other components in the framework
900 such that database connection and management details are hidden from
the other components. For example, in certain embodiments, the database
management component 916 may expose an API that includes database storage
and retrieval functionality to components of the framework 900. In other
words, a medical sensing workflow component may be able to transmit
diagnostic data to a local and/or remote database such as a DICOM or PACS
server via the database component without being aware of database
connection details. In other embodiments, the database management
component 916 may be operable to perform additional and/or different
database services such as data formatting services that prepare
diagnostic data for database archival.

[0092] As mentioned above, the processing framework 900 of the imaging
system 101 is operable to receive and process medical data associated
with one or a plurality of modalities. In multi-modal embodiments, the
processing framework 900 includes a plurality of modular acquisition
components and workflow components that are respectively associated with
different medical sensing and diagnostic modalities. For instance, as
shown in the illustrated embodiment of FIG. 9, the processing framework
900 includes an IVUS acquisition component 920 and an IVUS workflow
component 922 that are respectively configured to receive and process
IVUS medical sensing data from the IVUS PIM 112. In accordance with the
modular and extensible nature of the processing framework 900, any number
of additional acquisition and workflow components may be independently
added to the framework as denoted by the modality "N" acquisition
component 924 and the modality "N" workflow component 926 that acquire
and process data from a modality "N" PIM 928. For example, in certain
embodiments, the imaging system 101 may be communicatively coupled to the
OCT PIM 114, the ECG system 116, a fractional flow reserve (FFR) PIM, an
FL-IVUS PIM, and an ICE PIM. In other embodiments, additional and/or
different medical sensing, treatment, or diagnostic devices may be
coupled to the imaging system 101 via additional and/or different data
communication connections known in the art. In such a scenario, in
addition to the IVUS acquisition module 920, the processing framework 900
may include an FFR acquisition component to receive FFR data from an FFR
PIM, an FL-IVUS acquisition component to receive FL-IVUS data from an
FL-IVUS PIM, an ICE acquisition component to receive ICE data from an ICE
PIM, and an OCT acquisition component is operable to receive OCT data
from an OCT PIM. In this context, medical data communicated between the
executable components of the processing framework 900 and the
communicatively coupled medical devices (e.g., PIMs, catheters, etc.) may
include data collected by sensors, control signals, power levels, device
feedback, and other medical data related to a sensing, treatment, or
diagnostic procedure. Further, in certain embodiments, patient treatment
devices may be communicatively coupled to the imaging system 101 such as
devices associated with radiofrequency ablation (RFA), cryotherapy, or
atherectomy and any PIMs or other control equipment associated with such
treatment procedures. In such an embodiment, the modality "N" acquisition
component 924 and the modality "N" workflow component 926 may be
configured to communicate with and control the treatment devices such as
by relaying control signals, relaying power levels, receiving device
feedback, and receiving data collected by sensors disposed on the
treatment devices.

[0093] In one embodiment, once the acquisition components 920 and 924 have
received data from connected medical sensing devices, the components
packetize the data into messages to facilitate intersystem communication.
Specifically, the components may be operable to create a plurality of
messages from an incoming digital data stream, where each message
contains a portion of the digitized medical sensing data and a header.
The message header contains metadata associated with the medical sensing
data contained within the message. Further, in some embodiments, the
acquisition components 920 and 924 may be operable to manipulate the
digitized medical sensing data in some way before it is transmitted to
other portions of the framework 900. For example, the acquisition
components may compress the sensing data to make intersystem
communication more efficient, or normalize, scale or otherwise filter the
data to aid later processing of the data. In some embodiments, this
manipulation may be modality-specific. For example, the IVUS acquisition
component 920 may identify and discard redundant IVUS data before it is
passed on to save processing time in subsequent steps. The acquisition
components 920 and 924 may additionally perform a number of tasks related
to the acquisition of data including responding to interrupts generated
by data buses (e.g., PCIe, USB), detecting which medical sensing devices
are connected to imaging system 101, retrieving information about
connected medical sensing devices, storing sensing device-specific data,
and allocating resources to the data buses. As mentioned above, the data
acquisition components are independent from each other and may be
installed or removed without disrupting data acquisition by other
components. Additionally, acquisition components are independent of
underlying data bus software layers (for example, through the use of
APIs) and thus may be created by third parties to facilitate acquisition
of data from third party medical sensing devices.

[0094] The workflow components of the processing framework, such as the
IVUS workflow component 922, receive unprocessed medical sensing and/or
diagnostic data from respective acquisition components via the message
delivery component 910. In general, the workflow components are
configured to control the acquisition of medical sensing data such as by
starting and stopping data collection at calculated times, displaying
acquired and processed patient data, and facilitating the analysis of
acquired patient data by a clinician. As an aspect of this, the workflow
components are operable to transform unprocessed medical data gathered
from a patient into diagnostic images or other data formats that enable a
clinician to evaluate a patient's condition. For example, an IVUS
workflow component 922 may interpret IVUS data received from the IVUS PIM
112 and convert the data into human-readable IVUS images. In one
embodiment, a software stack within the framework may expose a set of
APIs with which the workflow component 922 and other workflow components
in the framework may call to access system resources such as the
computational resources, the message delivery component 910, and
communication resources. After processing acquired data, the
modality-centric workflow components may transmit one or messages
containing the processed data to other components within the framework
900 via the message delivery component 910. In some embodiments, before
sending such messages, the components may insert a flag in the header
indicating that the message contains processed data. Additionally, in
some embodiments, after processing medical sensing data, the components
may utilize the database management component 916 to transmit the
processed data to archival systems such as a locally attached mass
storage device or the network-based PACS server 127. In accordance with
the modular architecture of the processing framework 900, the workflow
components 922 and 926 are independent of each other and may be installed
or removed without disrupting other components, and may be written by
third parties. Further, due to their independence, they may be are
operable to process signaling and imaging data from multiple medical
sensing devices concurrently.

[0095] The processing framework 900 additionally includes a
co-registration interface component 930 and a co-registration workflow
component 932 that are configured to acquire and process data from any
number of data collection tools 934 and co-register the acquired data
with data acquired by one of the other acquisition components within the
framework. In more detail, the co-registration interface component 930
may be operable to communicatively interface with medical data
acquisition tools associated with any number of modalities, such as the
ECG device 116 or the angiography system 117 of FIG. 1A. In certain
embodiments, the interface component 930 may be operable to standardize
and/or transform incoming modality data such that it may be co-registered
with other sensing data acquired by the imaging system 101. As medical
data is being acquired by the co-registration interface component 930,
the co-registration workflow component 932 is configured to facilitate
the co-registration of data from different modalities such as by
spatially or temporally synchronizing data collection among medical
sensing devices, aligning two or more acquired data sets based on spatial
or temporal registration markers, and generating co-registered diagnostic
images or other human-readable data that enable a clinician to evaluate a
patient's condition. Further, in other embodiments, the co-registration
workflow component 932 may be operable to spatially co-register
catheter-gathered data in a two-dimensional (2-D) or three-dimensional
(3-D) space using previously-generated 2-D images or 3-D models. For
example, a catheter-based sensing tool may include fiducials that are
tracked to generate position data during a sensing procedure, and the
co-registration workflow component 932 may register this position data
against previously acquired MRI data. Still further, the co-registration
workflow component 932 may facilitate co-registration of multi-modality
data acquired by native acquisition components within the framework 900
such as the IVUS acquisition component 920 and modality "N" acquisition
component 924. Additionally, in some embodiments, a real-time clock may
be integrated into the co-registration workflow component 932. U.S.
Provisional Patent Application No. 61/473,591, entitled "DISTRIBUTED
MEDICAL SENSING SYSTEM AND METHOD", discloses temporally synchronizing
medical sensing data collection in more detail and is hereby incorporated
by reference in its entirety.

[0096] As discussed above in association with FIG. 1A, a clinician
utilizing the imaging system 101 may control workflows and view
diagnostic images through the main controller 120 and the bedside
controller 118. The main controller 120 and the bedside controller 118
respectively include user interface (UI) framework services 940 and 942
that support a plurality of user interface (UI) extensions (or
components). In general, the UI extensions supported by the UI framework
services 940 and 942 respectively correspond to medical sensing
modalities and are operable to render a user interface for control of the
associated acquisition workflow and display of processed sensing data.
Similar to the processing framework 900, the UI frameworks 940 and 942
are extensible in that they support UI extensions that are independent of
one another. That is, its modular design allows the UI frameworks 940 and
942 to be extended to accommodate additional medical sensing modality
user interfaces without impacting existing user interfaces or requiring
changes to the underlying UI architectures. In the illustrated
embodiment, the main controller 120 includes a system UI extension 944
that renders a user interface containing core system controls and
configuration options. For example, a clinician may startup, shutdown or
otherwise manage the imaging system 101 using the user interface rendered
by the system UI extension 944. In one embodiment, the components of the
main controller 120 may be considered part of the processing framework
900. The IVUS UI extensions 946 and 948 render user interfaces for the
main controller 120 and bedside controller 118, respectively. For
example, the IVUS UI extensions 946 and 948 may render and display the
touch screen buttons used to control an IVUS workflow and also render and
display the IVUS diagnostic images created by the IVUS workflow component
922. Similarly, the modality "N" UI extensions 950 and 952 render
controls and images associated with a modality "N" workflow.

[0097] In one embodiment, the UI framework services 940 and 942 may expose
APIs with which the UI extensions may call to access system resources
such as a look-and-feel toolbox and error handling resources.
Look-and-feel toolbox APIs enable the UI extensions to present a
standardized user interface with common buttons, parallel workflow
formats, and data presentation schemes for different modality workflows.
In this manner, clinicians may more easily transition between acquisition
modalities without additional user interface training. Further,
co-registration UI extensions may present and/or combine processed image
or signaling data from multiple modalities. For instance, a UI extension
may display an electrocardiogram (ECG) wave adjacent to IVUS imaging data
or may display an IVUS image overlaid with borders that were previously
drawn on an OCT image. Further, in some embodiments, the UI framework
services 940 and 942 may include a multi-tasking framework to coordinate
concurrently executing UI extensions. For instance, in the event the
imaging system 101 is simultaneously acquiring data associated with more
than one modality, the UI framework services 940 and 942 may present the
user with a modality selector screen on which a desired user interface
may be selected.

[0098] The UI framework service 940 communicates with the components of
the processing framework 900 via the message delivery component 910. As
shown in the illustrated embodiment of FIG. 9, the bedside controller 118
may be communicatively coupled to the processing framework 900 via a
network connection 954. The network connection 954 may be any type of
wired of wireless network connection such as an Ethernet connection or
IEEE 802.11 Wi-Fi connection. Alternatively, one or both of the main and
bedside controllers 120 and 118 may communicate with the processing
framework 900 via a local bus connection such as a (PCIe) data bus
connection, a USB connection, a Thunderbolt connection, a FireWire
connection, or some other high-speed data bus connection. Further, in the
illustrated embodiment of FIG. 9, the bedside controller includes a
message delivery component 956 that is configured to facilitate
message-based communication between the UI extensions in the bedside
controller 118 and the components in the processing framework 900. In
certain embodiments, the message delivery component 956 may extract
diagnostic image data from network communication packets as they arrive
over the network connection 954.

[0099] The processing framework 900 includes additional components that
allow a clinician to access and/or control workflows executing in the
multi-modality imaging system 101. For example, the framework 900
includes a remote access component 960 that communicatively couples the
network console 130 (FIG. 1A) to the processing framework 900. In one
embodiment, the remote access component 960 is operable to export control
functionality of the imaging system 101 to the network console 130, so
that the network console may present workflow control functions in its
user interface. In certain embodiments, the remote access component 960
may receive workflow commands from the network console 130 and forward
them to a remote access workflow component 962. The remote access
workflow component 962 may dictate the set of commands and diagnostic
data to which a remote user may access through the network console 130.
Further, the legacy control component 964 and legacy control workflow
component 966 provide some level of access to modality workflow control
and data to users of legacy consoles 968 (e.g. button consoles, mice,
keyboards, standalone monitors).

[0100] In one embodiment, the core system components of the processing
framework 900 and the additional components such as the modality-related
components may be implemented as processor-executable software stored on
non-transitory, computer-readable storage media, but in alternative
embodiments, these components may be implemented as hardware components
such as special purpose microprocessors, Field Programmable Gate Arrays
(FPGAs), microcontrollers, graphics processing units (GPU), digital
signal processors (DSP). Alternatively, the components of the processing
framework may be implemented as a combination of hardware and software.

[0101] One of ordinary skill in the art will recognize that the processing
framework 900 of FIG. 9 is simply an example embodiment and, in
alternative embodiments, the framework may include different and/or
additional components configured to carry out various medical sensing
workflows. For instance, the processing framework 900 may further include
executable components configured for the evaluation of a stenosis of a
human blood vessel or configured to facilitate control of
computer-assisted surgery or remotely-controlled surgery.

[0102] Referring now to FIG. 10, illustrated is a functional block diagram
of portions of the medical system 100 of FIGS. 1A, 1B, and 1C including a
user interface component 1000 for configuring the display of medical
sensing data according to some embodiments of the medical system 100. In
general, the user interface component 1000 receives display attributes
from a user and, based on the attributes, controls the acquisition,
processing, and/or presentation of the medical data. In this way, the
user interface component 1000 allows operators to zero in on relevant
data, to reduce screen clutter, and to improve the quality of displayed
data. The user interface component 1000 can also conserve system
resources by selectively processing only the data to be displayed. This
efficiency can improve system responsiveness and user experience.

[0103] The user interface component 1000 includes a display engine 1002
that presents a set of display controls to a user and receives a
user-selected display attribute. Accordingly, the display engine 1002 is
communicatively coupled to a controller 1004, which includes a user input
device 1006 and a user display device 1008. Examples of suitable user
input devices 1006 include, but are in no way limited to, keyboards,
keypads, mice, trackballs, digital pens, touch-based interfaces,
gesture-based interfaces, verbal and speech-recognition interfaces,
adaptive interfaces, cameras, motion-sensing interfaces, and/or other
user input devices known to one of skill in the art.

[0104] In addition to receiving display attributes directly from the user,
the display engine 1002 may also receive display attributes from a
database. In some such embodiments, the user interface component 1000
further includes a display attribute database 1010 communicatively
coupled to the display engine 1002. The display engine 1002 utilizes the
display attribute database 1010 to save and restore display attributes,
to edit attributes, and to create and distribute new attributes.

[0105] The display attribute governs the presentation of the data to the
user. As disclosed above, a multi-modality imaging system (e.g., imaging
system 101) may receive sets of medical sensing data collected from a
number of individual sensors and corresponding to a wide array of sensing
modalities including pressure data, flow data, IVUS data, photoacoustic
IVUS data, FL-IVUS data, FFR determinations, CFR determinations, OCT
data, transesophageal echocardiography data, image-guided therapy data,
other suitable medical data, and/or combinations thereof. In various
embodiments, the received display attribute applies to a portion of the
available medical data, multiple portions of the medical data, and/or all
of the medical data. Accordingly, the display attribute may specify the
portion of the medical data to which it is to be applied. The display
attribute may specify the applicable dataset by sensor, by sensing
instrument, by modality, by a window of time, by other suitable divisions
and/or by combinations thereof, and the display attribute may modify the
specified dataset independent of other datasets received by the system.
Thus, in an embodiment, a display attribute specifies a display
characteristic for data collected by a first, relatively proximal, sensor
independent of data collected by a second, relatively distal, sensor
despite that both sensors are incorporated into a single sensing
instrument. In another embodiment, a display attribute specifies a
display characteristic for data of a first modality independent of data
of a second modality despite that both datasets are collected by a single
physical sensor. This can be extended to other suitable divisions.

[0106] The display attribute may include static values as well as
dependent or dynamic values. For example, a display attribute may specify
a value that depends on another parameter or data value. In some
exemplary embodiments, the display attributes may specify values that
depend on user preferences, an operative course of a medical procedure
being performed, patient information, the subset of data to which the
display attribute applies, a subset of data independent of the display
attribute, a status indicator, and/or a sensor attribute. In one such
embodiment, the display attribute specifies a set of values that the
display engine 1002 selects between based on the hospital or surgical
facility performing the procedure. In another such embodiment, the
display attribute specifies physician-specific values.

[0107] Based on the display attribute, the display engine 1002 generates a
set of instructions to govern the acquisition, processing, and display of
the applicable data. With respect to data acquisition instructions, the
instructions may direct the operation of sensors, sensing instruments,
supporting devices such as a PIM or imaging system, and/or other data
processing components. Exemplary instructions designate sensor operating
power, amplifier gain, and/or any other applicable operating parameter.
In some embodiments, a generated instruction halts or prevents the
collection of data. To reduce power, system load, and potential signal
interference, in some such embodiments, halting includes disabling or
powering down the sensor (e.g., ultrasound transducer, pressure sensor,
flow meter, OCT sensor, etc.), corresponding interface components,
processing components, and/or other related components when the display
attribute signals that the sensor data will not be displayed. In some
embodiments utilizing optical sensors, halting includes disabling or
powering down a corresponding laser emitter.

[0108] With respect to data processing instructions, the generated
instructions may direct the operation of sensors, sensing instruments,
supporting devices such as a PIM or imaging system, and/or other data
processing components. Exemplary instructions designate a sampling rate,
a baseline correction factor, an IVUS focusing parameter, a pseudo-color
conversion scheme, and/or another applicable operating parameter. In one
such example, the generated instructions activate a motion detection
algorithm, such as blood flow analysis, and specify one or more IVUS
transducer to supply the data.

[0109] With respect to the display of the processed data, the instructions
may likewise direct the operation of sensors, sensing instruments,
supporting devices such as a PIM or imaging system, and/or other data
processing components.

[0110] The display engine 1002 provides the generated instructions to the
respective components of the medical system 100 including the sensors,
the sensing instruments, the supporting devices, and/or other data
processing components. For example, in some embodiments, the display
engine 1002 provides instructions based on the display attribute to a
tissue characterization engine 1012. In brief, tissue characterization
processes such as Virtual Histology® (a trademark of Volcano
Corporation) compare received medical sensing data against data collected
from known samples in order to identify constituent tissues and
structures. Recognized tissues may be highlighted upon display using
color, markers, outlines, and other signifiers for easy identification by
the operator. U.S. Pat. No. 7,074,188, entitled "SYSTEM AND METHOD OF
CHARACTERIZING VASCULAR TISSUE, U.S. Pat. No. 7,175,597, entitled
"NON-INVASIVE TISSUE CHARACTERIZATION SYSTEM AND METHOD," and U.S. Pat.
No. 7,988,633, entitled "APPARATUS AND METHOD FOR USE OF RFID CATHETER
INTELLIGENCE," disclose tissue characterization in greater detail and are
hereby incorporated by reference in their entirety. Using the display
engine 1002, operators can control the display of recognized tissues in
order to highlight important structures and to reduce overall clutter. In
some embodiments, the display engine 1002, by specifying a subset of the
total data for the tissue characterization engine 1012 to analyze or
exclude, improves characterization speed and frees resources for other
types of image processing.

[0111] Thus, in some embodiments, the display engine 1002 supports display
attributes that relate to tissue characterization. Such display
attributes may specify the dataset and/or the tissues (e.g., thrombus,
plaque, adventitia, fibrous tissue, fibro-lipidic tissue, calcified
necrotic tissue, calcific tissue, collagen composition, cholesterol,
stent, vessel wall, etc.) to which the attributes apply. In an exemplary
embodiment, a display attribute specifies that the attribute applies to
data collected by a particular sensor and to plaque structures identified
therein. In a further exemplary embodiment, a display attribute specifies
that the attribute applies to IVUS sensor data and applies to all
structures except stents.

[0112] The display engine 1002 may therefore support a number of display
attributes that are particularly relevant to tissue characterization. For
example, a display attribute may specify a threshold value, an identifier
(e.g., color, marker shape, outline, etc.) to associate with a tissue
type, whether to hide, display, or dim particular tissue types, and/or
may specify other relevant tissue characterization parameters. Display
attributes may include dependent or dynamic values in addition to static
values. Based on the display attribute, the display engine 1002 generates
a set of instructions to govern the tissue characterization process and
the display of characterized data. These instructions may be executed by
the tissue characterization engine 1012 and/or other suitable components
of the medical system 100 including the imaging system 101.

[0113] In addition to providing instructions to other components, in some
embodiments, the display engine 1002 further executes one or more of the
generated instructions during the display of the relevant sensing data.
In one such embodiment, the display engine 1002 executes an instruction
that specifies a pseudo-color scheme during a conversion of signal
intensity into a color value. The display engine 1002 then presents the
converted pseudo-color data at the user display device 1008. In a further
such embodiment, the display engine 1002 executes an instruction that
adjusts the contrast of an identified subset of an IVUS image
corresponding to a hot spot produced by a stent. The display engine 1002
then presents the adjusted IVUS image at the user display device 1008. In
a further such embodiment, the display engine 1002 maintains a tissue
characterization identifier table based on the instructions generated in
response to the display attributes. When displaying characterized sensing
data, the display engine 1002 applies identifiers from the table to
highlight identified tissues.

[0114] Portions of the user interface component 1000 may be implemented,
in whole or in part, as processor-executable software stored on
non-transitory, computer-readable storage media and/or as hardware
components such as special purpose microprocessors, FPGAs,
microcontrollers, graphics processing units, and DSPs. In some
embodiments, portions of the user interface component 1000 are
incorporated into components of the medical system 100 described with
reference to FIGS. 1A, 1B, and 1C and FIGS. 2-9. For example, in some
such embodiments, controller 1004 is a component of a bedside controller
118, a main controller 120, a boom display 122, and/or a network console
130 described with reference to FIG. 1A. As a further example, in some
such embodiments, the display engine 1002 is incorporated into a UI
framework service 940 of a main controller 120, a UI framework service
942 of a bedside controller 118, and/or a UI extension such as IVUS UI
extension 946 or IVUS UI extension 948 described with reference to FIG.
9. In other embodiments, the user interface component 1000 is a separate
and distinct component of the multi-modality medical system 100.

[0115] One of ordinary skill in the art will recognize that the above
examples of display attributes and instructions are merely exemplary
embodiments and are not limiting. In further embodiments, the display
engine 1002 receives further types of display attributes and provides
additional functionality allowing users to tailor the display to their
liking.

[0116] FIG. 11 is a diagram of an exemplary user interface 1100 for
customizing the display of multi-modality medical data according to some
embodiments of the present disclosure. The user interface 1100 may be
displayed on a user display such as the user display 1008 described with
reference to FIG. 10. The user interface 1100 represents one possible
arrangement for displaying the information presented by the
multi-modality processing system 100 and more specifically presented by
the display engine 1002. One skilled in the art will recognize that
alternate arrangements are both contemplated and provided for.

[0117] In the illustrated embodiment, the user interface 1100 includes one
or more display panes 1102 and 1104 for displaying medical sensing data
corresponding to one or more modalities. Examples of medical sensing data
include IVUS data, forward-looking IVUS data, flow velocity, pressure
data, FFR determinations, CFR determinations, OCT data, and
trans-esophageal echocardiography data. In the illustrated embodiment,
pane 1102 displays a first subset of data corresponding to a first
modality, and pane 1104 displays a second subset of data corresponding to
a second modality. The first and second modalities may be different. The
user interface 1100 allows the user to select independent display
attributes for the first subset of data of pane 1102 and the second
subset of data of pane 1104. Display attribute options may be presented
via checkboxes, exclusive and non-exclusive lists, radio buttons, and/or
other suitable interface schemes. In the illustrated embodiment, display
attributes for the first subset of data of pane 1102 are presented via
tabs 1106 and display attributes for the second subset of data of pane
1104 are presented via tabs 1108, although this is merely exemplary and
other arrangements including dropdown menus, toolbars, trees, and other
suitable arrangements are provided for. Upon user selection of a display
attribute, the display attribute is applied to the corresponding data
subset or subsets and the display 1100 is updated accordingly.

[0118] FIG. 12 is a diagram of an exemplary user interface 1200 for
customizing the display of characterized tissue according to some
embodiments of the present disclosure. The user interface 1200 may be
displayed on a user display such as the user display 1008 described with
reference to FIG. 10. The user interface 1200 represents one possible
arrangement for displaying the information presented by the
multi-modality processing system 100 and more specifically presented by
the display engine 1002. One skilled in the art will recognize that
alternate arrangements are both contemplated and provided for.

[0119] In the illustrated embodiment, the user interface 1200 includes one
or more display panes 1202 for displaying medical sensing data
corresponding to one or more modalities. The user interface 1200 may also
include one or more display attribute panes 1204. The display attribute
pane 1204 presents user-selectable display attributes corresponding to a
tissue characterization process via checkboxes 1206, exclusive and
non-exclusive lists 1208, radio buttons, and other suitable interface
schemes. In the illustrated embodiment, the display attribute pane 1204
presents the display attribute options in categories presented as tabs
1210, although this is merely exemplary and other arrangements including
dropdown menus, toolbars, trees, and other suitable arrangements are
provided for. Upon user selection of display attribute, the display
attribute is applied to the corresponding data and the display is
updated. This may include updating a tissue marker (e.g., marker 1212).

[0120] As disclosed above in detail, a medical imaging system (e.g.,
imaging system 101 of FIG. 1A) receives, directs, processes, and displays
medical sensing data. The medical imaging system may receive considerable
amounts of data collected from a number of individual sensors and
corresponding to a wide array of sensing modalities. For example, in
various embodiments, the medical imaging system receives pressure data,
flow data, IVUS data, photoacoustic IVUS data, FL-IVUS data, FFR
determinations, CFR determinations, OCT data, transesophageal
echocardiography data, image-guided therapy data, other suitable medical
data, and/or combinations thereof. To assist users in sifting through
this wealth of information, the medical imaging system may adjust the
collection, processing, and display of the underlying data at the user's
command. Methods of responding to these display attributes are disclosed
with reference to FIGS. 13-15.

[0121] FIG. 13 is a flow diagram of a method 1300 of collecting medical
sensing data based on a display attribute according to some embodiments
of the present disclosure. It is understood that additional steps can be
provided before, during, and after the steps of method 1300, and some of
the steps described can be replaced or eliminated for other embodiments
of the method. Referring to block 1302 of the method 1300, the medical
imaging system receives the display attribute. The display attribute may
be received via a user input and/or an external storage resource such as
a display attribute database. The display attribute governs the
presentation of the data to the user. The display attribute may be
applied to a single data subset, multiple data subsets, and/or all the
available medical data. Accordingly, in the embodiments of FIG. 13, the
display attribute is applied to a first data subset, but not necessarily
a second data subset. First and second subsets may be defined by sensor,
by sensing instrument, by modality, by a window of time, by other
suitable divisions and/or by combinations thereof. In some embodiments,
the display attribute specifies the subsets to which it is to be applied.

[0122] The display attribute may include static values, dynamic values,
and/or dependent values. In some exemplary embodiments, the display
attributes may specify values that depend on user preferences, an
operative course of a medical procedure being performed, a medical
facility performing the procedure, patient information, the subset of
data to which the display attribute applies, a subset of data independent
of the display attribute, a status indicator, and/or a sensor attribute.

[0123] In block 1304, the medical system generates a set of instructions
to govern the acquisition of the first data subset based on the display
attribute. In some embodiments, the instructions designate sensor
operating power, amplifier gain, and/or any other applicable operating
parameter. In some embodiments, a generated instruction halts or prevents
the collection of data, which may include disabling an associated sensor
and, in the case of optical sensors, may include disabling a
corresponding laser emitter. In some embodiments, a generated instruction
causes data to be collected and stored but not processed in real-time.
This frees up real-time resources while ensuring that the data is
available for later evaluation. In block 1306, at least one instruction
of the set is provided in order to collect the first data subset
according to the display attribute. In various exemplary embodiments, the
instruction is provided to a component of the medical system such as a
sensor (e.g., ultrasound transducer, pressure sensor, flow sensor, OCT
sensor, etc.), a sensing instrument (e.g., catheter, guide catheter,
guide wire, etc.), a supporting device such as a PIM or an imaging
system, and/or other data acquisition component.

[0124] In block 1308, an instruction is provided in order to collect the
second data subset. The instruction to collect the second data subset is
independent of the display attribute. In block 1310, the set of medical
data including the first and second subsets, the first being collected
according to the display attribute is received by the medical system. In
block 1312, the set of medical data is displayed according to the display
attribute.

[0125] FIG. 14 is a flow diagram of a method 1400 of processing and
displaying medical sensing data based on a display attribute according to
some embodiments of the present disclosure. It is understood that
additional steps can be provided before, during, and after the steps of
method 1400, and some of the steps described can be replaced or
eliminated for other embodiments of the method. In block 1400, a medical
imaging system receives a set of medical data that contains first and
second subsets of data. Data subsets may be defined by sensor, by sensing
instrument, by modality, by a window of time, by other suitable divisions
and/or by combinations thereof.

[0126] In block 1404, the medical imaging system receives a display
attribute. The display attribute may be applied to a single data subset,
multiple data subsets, and/or all available medical data. Accordingly, in
the embodiments of FIG. 14, the display attribute is applied to the first
data subset, but not necessarily the second data subset. In some
embodiments, the display attribute specifies the subsets of the set of
medical data to which it is to be applied.

[0127] The display attribute governs the presentation of data to the user.
The display attribute may include static values, dynamic values, and/or
dependent values. In some exemplary embodiments, the display attributes
specify values that depend on user preferences, an operative course of a
medical procedure being performed, a medical facility performing the
procedure, patient information, the subset of data to which the display
attribute applies, a subset of data independent of the display attribute,
a status indicator, and/or a sensor attribute.

[0128] In block 1406, the medical system generates a set of instructions
that affect the processing of the first data subset based on the display
attribute. In some exemplary embodiments, the instructions designate a
threshold value, a pseudo-color conversion scheme, and a display state
from the group consisting of a shown state, a dimmed state, and a hidden
state. In block 1408, at least one instruction of the set is provided in
order to process the first data subset according to the display
attribute. In various exemplary embodiments, the instruction is provided
to a component of the medical system such as a sensor (e.g., ultrasound
transducer, pressure sensor, flow meter, OCT sensor, etc.), a sensing
instrument (e.g., a catheter, guide catheter, guide wire, etc.), a
supporting device such as a PIM or an imaging system, and/or other data
acquisition component.

[0129] In block 1410, the medical system displays the first subset
according to the display attribute, and, in block 1412, the medical
system displays the second subset independent of the display attribute.

[0130] FIG. 15 is a flow diagram of a method 1500 of performing tissue
characterization based on a display attribute according to some
embodiments of the present disclosure. It is understood that additional
steps can be provided before, during, and after the steps of method 1500,
and some of the steps described can be replaced or eliminated for other
embodiments of the method. In block 1502, a medical imaging system
receives a set of medical data. The set may include various subsets
corresponding to disparate sensors, modalities, and/or sensing
instruments.

[0131] In block 1504, the system receives a display attribute to be
applied to at least one subset of the medical data. The display attribute
may also apply to select tissues to be characterized while not
necessarily applying to other tissue types. Accordingly, such display
attributes may specify the dataset and/or the tissues (e.g., thrombus,
plaque, adventitia, fibrous tissue, fibro-lipidic tissue, calcified
necrotic tissue, calcific tissue, collagen composition, cholesterol,
stent, vessel wall, etc.) to which the attributes apply. Additionally,
the display attribute may include static values, dynamic values, and/or
dependent values. In block 1506, the medical system generates a set of
instructions based on the display attribute for use in a tissue
characterization process to be performed on the set of medical data. For
example, the instructions may specify a threshold value, an identifier
(e.g., color, marker shape, outline, etc.) to associate with a tissue
type, whether to hide, display, or dim particular tissue types, and/or
may specify other relevant tissue characterization parameters.

[0132] In block 1508, at least one instruction of the set is provided for
use in the tissue characterization process. In various exemplary
embodiments, the instruction is provided to a component of the medical
system such as a sensor (e.g., ultrasound transducer, pressure sensor,
flow meter, OCT sensor, etc.), a sensing instrument (e.g., a catheter,
guide catheter, guide wire, etc.), a supporting device such as a PIM or
an imaging system, and/or other data acquisition component. In block
1510, the tissue characterization process is performed using the provided
instruction. The tissue characterization process identifies constituent
tissue elements from the medical data and assigns tissue identifiers to
the constituent tissue elements to identify them upon display. In block
1512, the medical system displays the characterized set of medical data
and the tissue identifiers.

[0133] FIG. 16 is a flow diagram of a method 1600 of locating a structure
within a vessel according to some embodiments of the present disclosure.
It is understood that additional steps can be provided before, during,
and after the steps of method 1600, and some of the steps described can
be replaced or eliminated for other embodiments of the method. In block
1602, a flexible elongate member (e.g., catheter, guide catheter, guide
wire, etc.) of a sensing device is advanced into a vessel. The elongate
member incorporates a plurality of sensors disposed along a longitudinal
length of the elongate member. The plurality of sensors may include any
suitable medical sensors such as ultrasound transducers, photoacoustic
ultrasound transducers, pressure sensors, optical pressure sensors, flow
sensors, optical flow sensors, OCT transceivers, and/or other suitable
sensors, and the associated sensors may correspond to one or more
modalities including, flow, optical flow, IVUS, photoacoustic IVUS,
FL-IVUS, pressure, optical pressure, fractional flow reserve (FFR)
determination, coronary flow reserve (CFR) determination, optical
coherence tomography (OCT), transesophageal echocardiography,
image-guided therapy, other suitable modalities, and/or combinations
thereof.

[0134] In block 1604, a set of medical data measurements are obtained. The
set includes at least one measurement from each sensor of the plurality
of sensors. In block 1606, the measurements are compared across the
plurality of sensors. Comparing may include direct comparison between
sensors, comparison to a reference value such as those in a tissue
characterization database, comparison to a threshold, and/or other types
of comparisons. In some embodiments, comparing includes performing a
series of FFR calculations and comparing the FFR ratios to a threshold
that suggests that a stenosis lies between the proximal and distal
sensors. In some embodiments, comparing includes comparing IVUS and/or
OCT measurements to a tissue characterization database to detect one or
more of a thrombus, a plaque, adventitia, fibrous tissue, fibro-lipidic
tissue, calcified necrotic tissue, calcific tissue, collagen composition,
cholesterol, a stent, a vessel wall, and/or other structure. In block
1608, the comparison is used to detect a difference in a vascular
characteristic indicative of the structure of interest. The difference
may be an FFR ratio beyond a threshold, a variation in tissue, a
difference in signal intensity or character, and/or other suitable
differences. In block 1610, the difference is used to determine the
sensors in proximity to the structure of interest. For example, in the
case of an FFR ratio, the sensors in proximity may include the sensors
involved in the ratio calculation. In the case of a structure recognized
via a tissue characterization process, the sensors in proximity may
include the sensors that collected the characterized data from which the
structure was recognized. In block 1612, the location of the structure is
determined based on the sensors in proximity.

[0135] In some embodiments, once the structure is located, further
diagnostic analysis may be performed. In one such embodiment, individual
and cumulative effects of a plurality of stenoses are measured and
analyzed. In block 1614, a proximal pressure measurement is obtained for
each stenosis of the plurality of stenoses. The proximal measurement is
obtained from a sensor proximal to the stenosis and substantially between
the stenosis and any stenosis that happens to be proximal to the one
being measured. In block 1616, a distal pressure measurement is obtained
for the stenosis using a sensor distal to the stenosis and substantially
between the stenosis and any subsequent distal stenosis. In block 1618,
an individual pressure ratio is determined for the stenosis using the
collected distal and proximal sensor measurements.

[0136] In block 1620, a proximal pressure measurement for determining a
cumulative effect is obtained utilizing a sensor proximal to all of the
stenoses of the plurality of stenoses. In block 1622, a corresponding
distal pressure measurement is obtained using a sensor distal to all of
the stenoses of the plurality of stenoses. In block 1624, a cumulative
pressure ratio is determined for the plurality using the collected distal
and proximal sensor measurements.

[0137] In some embodiments, this further diagnostic analysis includes
repositioning a detailed sensing region of the elongate member to be
adjacent to the structure of interest. In an embodiment, this includes
adjusting the location of the elongate member of the vessel. The amount
by which the elongate member is advanced or withdrawn may be determined
based on the difference between the location of the structure determined
in block 1612 and the location of the detailed sensing region. Once the
detailed sensing region is positioned, subsequent measurements are
obtained using the sensors disposed within the detailed sensing region.
The subsequent measurements may correspond to a different modality than
the previous measurements. For example, in an embodiment, pressure
measurements are used to locate a stenosis, and IVUS measurements are
used to examine the stenosis in detail. In another exemplary embodiment,
structural IVUS measurements are used to locate a bifurcation, and
Doppler IVUS measurements are used to examine the bifurcation in detail.

[0138] Referring now to FIG. 17, in some embodiments, detailed
measurements along the length of a vessel may be made without
repositioning the elongate member. FIG. 17 is a flow diagram of a method
1700 of evaluating a vessel according to some embodiments of the present
disclosure. It is understood that additional steps can be provided
before, during, and after the steps of method 1700, and some of the steps
described can be replaced or eliminated for other embodiments of the
method. The method 1700 allows operators to perform high-level
measurements on a vessel and, based on the high-level measurements, to
select vascular segments to measure further without necessarily
relocating the sensing instrument. In block 1702, the sensing instrument,
such as a flexible elongate member, is advanced into a vessel such that a
sensing portion of the instrument extends through the region of the
vessel to be imaged. The sensing portion may include any suitable medical
sensors such as ultrasound transducers, pressure sensors, flow sensors,
OCT transceivers, and/or other suitable sensors, and the associated
sensors may correspond to one or more modalities including flow, optical
flow, IVUS, photoacoustic IVUS, FL-IVUS, pressure, optical pressure, FFR
determination, CFR determination, OCT, transesophageal echocardiography,
image-guided therapy, other suitable modalities, and/or combinations
thereof.

[0139] In block 1704, a first set of medical data measurements are
obtained using a first subset of the plurality of sensors. The first set
of medical data corresponds to a first modality such as flow, optical
flow, IVUS, photoacoustic IVUS, FL-IVUS, pressure, optical pressure, FFR
determination, CFR determination, OCT, transesophageal echocardiography,
image-guided therapy, other suitable modalities, and/or combinations
thereof. In block 1706, the first set of medical data is presented to a
user via a display device. A representation of the vascular region is
also presented via the display device. The representation may divide the
region into a collection of selectable vascular segments where each
segment has one or more sensors positioned to measure the segment. In
some embodiments, the medical data is given context by displaying the
medical data in conjunction with the vascular segments. In an embodiment
where the set of medical data includes pressure data used to determine
FFR ratios, each segment indicator is overlaid with an FFR ratio
calculated for the segment. In a further embodiment where the set of
medical data includes IVUS data, the IVUS data is overlaid with icons
indicating the corresponding segments.

[0140] In some embodiments, presenting the first set of medical data
includes highlighting an identified portion of the set of medical data.
In an exemplary embodiment where the medical data includes pressure data
used to determine FFR ratios, ratios less than a critical threshold and
suggesting a potential stenosis are highlighted. In an exemplary
embodiment where the medical data includes IVUS data, regions
corresponding to a bifurcation, a stenosis, a plaque, a vascular
dissection, a lesion, and/or a stent are highlighted.

[0141] The user may then select a segment of the vascular region to
analyze in further detail. In block 1708, a user input specifying a
segment is received. In block 1710, a second set of measurements is
obtained using a second subset of sensors that includes the sensors
positioned to measure the selected segment. Thus, the second set of
measurement data measures the selected segment of the vascular region.
Because the sensing instrument includes sensors arranged along the length
of the sensing portion, the second set of measurements can be obtained
without necessarily adjusting the position of the sensing portion. In
some embodiments where the sensing instrument includes a variety of
sensors arranged along the length, the second set of measurements
corresponds to a different modality than the first set of measurements.

[0142] In some embodiments, additional vascular segments can be selected
for further measurement without repositioning the sensing portion. In
block 1712, a second user input specifying a second segment of the vessel
region is received. In block 1714, a third set of measurements
corresponding to the second selected segment is obtained. The third set
of measurements is obtained without necessarily adjusting the position of
the sensing portion.

[0143] Referring now to FIG. 18, in some embodiments, the user can obtain
detailed measurements in a manner resembling a physical advance and
pullback of a narrow-window sensing device. FIG. 18 is a flow diagram of
a method 1800 of displaying medical data by simulating pullback of an
intravascular sensing device according to some embodiments of the present
disclosure. It is understood that additional steps can be provided
before, during, and after the steps of method 1800, and some of the steps
described can be replaced or eliminated for other embodiments of the
method. The method 1800 allows users to perform a virtual pullback
without necessarily moving the sensing device and without the delay and
risk of lost alignment caused by physical movement. In block 1802, a
sensing instrument, such as a flexible elongate member, having a
plurality of sensors is advanced into a vessel to be displayed. The
sensors may include any suitable medical sensors such as ultrasound
transducers, pressure sensors, flow sensors, OCT transceivers, and/or
other suitable sensors, and the associated sensors may correspond to one
or more modalities including flow, optical flow, IVUS, photoacoustic
IVUS, FL-IVUS, pressure, optical pressure, FFR determination, CFR
determination, OCT, transesophageal echocardiography, image-guided
therapy, other suitable modalities, and/or combinations thereof.

[0144] In block 1804, an imaging system divides the vessel into portions
and determines one or more sensors positioned to measure each portion of
the vessel. This may include collecting a preliminary set of medical data
measurements as disclosed in block 1704 of FIG. 17. In block 1806, the
system displays selectable indicators of each of the vascular portions
via a user display. This may be substantially similar to the display
disclosed in block 1706 of FIG. 17. In block 1808, the system receives a
user selection designating a vascular portion. In block 1810, medical
data is collected from the sensor or sensors positioned to measure the
designated portion. This medical data may correspond to a different
modality than the preliminary set of medical data. In block 1812, the
medical data is displayed. The display of the medical data simulates a
pullback of a sensing device without necessarily moving the sensing
instrument.

[0145] Although illustrative embodiments have been shown and described, a
wide range of modification, change, and substitution is contemplated in
the foregoing disclosure and in some instances, some features of the
present disclosure may be employed without a corresponding use of the
other features. Further, as described above, the components and
extensions described above in association with the multi-modality
processing system may be implemented in hardware, software, or a
combination of both. The processing systems may be designed to work on
any specific architecture. For example, the systems may be executed on a
single computer, local area networks, client-server networks, wide area
networks, internets, hand-held and other portable and wireless devices
and networks. It is understood that such variations may be made in the
foregoing without departing from the scope of the present disclosure.
Accordingly, it is appropriate that the appended claims be construed
broadly and in a manner consistent with the scope of the present
disclosure.